U.S. patent application number 11/843165 was filed with the patent office on 2008-07-24 for methods for sterilizing biological materials.
Invention is credited to Dawson Beall, Edward A. Horton, Randall S. Kent, Martin J. MacPhee.
Application Number | 20080176306 11/843165 |
Document ID | / |
Family ID | 22253204 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080176306 |
Kind Code |
A1 |
MacPhee; Martin J. ; et
al. |
July 24, 2008 |
Methods for Sterilizing Biological Materials
Abstract
Methods are disclosed for sterilizing biological products to
reduce the level of active biological contaminants such as viruses,
bacteria, yeasts, molds, mycoplasmas and parasites.
Inventors: |
MacPhee; Martin J.;
(Montgomery Village, MD) ; Kent; Randall S.;
(Thousand Oaks, CA) ; Horton; Edward A.; (Toronto,
CA) ; Beall; Dawson; (Gaithersburg, MD) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Family ID: |
22253204 |
Appl. No.: |
11/843165 |
Filed: |
August 22, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10694734 |
Oct 29, 2003 |
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11843165 |
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09533547 |
Mar 23, 2000 |
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10694734 |
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08573149 |
Dec 15, 1995 |
6171549 |
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09533547 |
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PCT/CA94/00401 |
Jul 22, 1994 |
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08573149 |
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08095698 |
Jul 22, 1993 |
5362442 |
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PCT/CA94/00401 |
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Current U.S.
Class: |
435/173.1 |
Current CPC
Class: |
A61L 2/0076 20130101;
A61L 2/0035 20130101; A61L 2/0029 20130101; A61L 2202/22
20130101 |
Class at
Publication: |
435/173.1 |
International
Class: |
C12N 13/00 20060101
C12N013/00 |
Claims
1-26. (canceled)
27. A method for reducing the level of active biological
contaminants or pathogens in bone, comprising contacting the bone
with a composition comprising DMSO, trehalose and mannitol; and
irradiating the bone-containing composition with gamma radiation,
wherein the total dose of gamma radiation is at least about 12
kGy.
28. The method of claim 27, wherein the bone-containing composition
is below ambient temperature during irradiation.
29. The method of claim 27, wherein the bone-containing composition
is at a temperature below its freezing point during
irradiation.
30. The method of claim 27, wherein the irradiation is applied at a
rate of at least about 0.1 kGy/hour to at least about 30.0
kGy/hour.
31. The method of claim 27, wherein the total dose of gamma
irradiation is at least about 20 kGy.
32. The method of claim 27, wherein the total dose of gamma
irradiation is at least about 26 kGy.
33. The method of claim 27, wherein the bone is demineralized bone
matrix.
34. The method of claim 27, further comprising adjusting or
maintaining the pH of the bone prior to irradiation.
35. The method of claim 27, further comprising reducing residual
solvent content of the bone prior to irradiation.
36. The method of claim 35, wherein the residual solvent is a
non-aqueous solvent.
37. The method of claim 35, wherein the residual solvent is an
aqueous solvent.
38. The method of claim 35, wherein the residual solvent content is
reduced to less than about 2.0%.
39. The method of claim 27, further comprising contacting the bone
with at least one sensitizer prior to irradiation.
40. The method of claim 27, wherein the active biological
contaminants or pathogens are selected from the group consisting of
viruses, bacteria, yeasts, molds, parasites, prions and
combinations thereof.
41. The method of claim 27 wherein the bone is maintained in an
inert atmosphere during irradiation.
42. The method of claim 27 wherein the bone is maintained under
vacuum during irradiation.
Description
[0001] This application is a continuation application of U.S.
application Ser. No. 10/694,734 (Oct. 29, 2003), which is a
continuation application of U.S. application Ser. No. 09/533,547
(Mar. 23, 2000), which is a continuation-in-part application of
U.S. application Ser. No. 08/573,149 (Dec. 15, 1995, now U.S. Pat.
No. 6,171,549), which is a continuation-in-part application of PCT
International Patent No. PCT/CA94/00401 (Jul. 22, 1994), which is a
continuation-in-part application of U.S. application Ser. No.
08/095,698 (filed Jul. 22, 1993, now U.S. Pat. No. 5,362,442), all
of which are herein incorporated by reference in their
entireties.
FIELD OF THE INVENTION
[0002] The present invention relates to methods for sterilizing
biological materials to reduce the level of active biological
contaminants therein, such as viruses, bacteria, yeasts, molds,
mycoplasmas and/or parasites.
BACKGROUND OF THE INVENTION
[0003] Several products that are prepared from human, veterinary or
experimental use may contain unwanted and potentially dangerous
contaminants such as viruses, bacteria, yeasts, molds, mycoplasmas
and parasites. Consequently, it is of utmost importance that any
biologically active contaminant in the product be inactivated
before the product is used. This is especially critical when the
product is to be administered directly to a patient, for example in
blood transfusions, organ transplants and other forms of human
therapies. This is also critical for various biotechnology products
which are grown in media which contain various types of plasma and
which may be subject to mycoplasma or other viral contaminants.
[0004] Previously, most procedures have involved methods that
screen or test products for a particular contaminant rather than
removal or inactivation of the contaminant from the product.
Products that test positive for a contaminant are merely not used.
Examples of screening procedures include the testing for a
particular virus in human blood from blood donors. Such procedures,
however, are not always reliable and are not able to detect the
presence of viruses in very low numbers. This reduces the value or
certainty of the test in view of the consequences associated with a
false negative result. False negative results can be life
threatening in certain cases, for example in the case of Acquired
Immune Deficiency Syndrome (AIDS). Furthermore, in some instances
it can take weeks, if not months, to determine whether or not the
product is contaminated.
[0005] More recent efforts have focused in methods to remove or
inactivate contaminants in the products. Such methods include heat
treating, filtration and the addition of chemical inactivants or
sensitizers to the product. Heat treatment requires that the
product be heated to approximately 60.degree. C. for about 70 hours
which can be damaging to sensitive products. Heat inactivation can
destroy up to 50% of the biological activity of the product.
Filtration involves filtering the product in order to physically
remove contaminants. Unfortunately this method may also remove
products that have a high molecular weight. Further, in certain
cases small viruses may not be removed by the filter because of the
larger molecular structure of the product. The procedure of
chemical sensitization involves the addition of noxious agents
which bind to the DNA/RNA of the virus and which are activated
either by UV or ionizing radiation to produce free radicals which
break the chemical bonds in the backbone of the DNA/RNA of the
virus or complex it in such a way that the virus can no longer
replicate. This procedure requires that unbound sensitizer is
washed from cellular products since the sensitizers are toxic, if
not mutagenic or carcinogenic, and can not be administered to a
patient.
[0006] Irradiating a product with gamma radiation is another method
of sterilizing a product. Gamma radiation is effective in
destroying viruses and bacteria when given in high total doses
(Keathly et al., "Is There Life After Irradiation? Part 2,"
BioPharm July-August, 1993, and Leitman, Use of Blood Cell
Irradiation in the Prevention of Post Transfusion Graft-vs-Host
Disease," Transfusion Science 10:219-239 (1989)). The published
literature in this area, however, teaches that gamma radiation can
be damaging to radiation sensitive products, such as blood. In
particular, it has been shown that high radiation doses are
injurious to red cells, platelets and granulocytes (Leitman). U.S.
Pat. No. 4,620,908 discloses that protein products must be frozen
prior to irradiation in order to maintain the viability of the
protein product. This patent concludes that "[i]f the gamma
irradiation were applied while the protein material was at, for
example, ambient temperature, the material would be also completely
destroyed, that is the activity of the material would be rendered
so low as to be virtually ineffective." Unfortunately, many
sensitive biologicals, such as blood, would lose viability and
activity if subjected to freezing for irradiation purposes and then
thawing prior to administration to a patient.
[0007] In view of the difficulties discussed above, there remains a
need for methods of sterilizing biological materials that are
effective for reducing the level of active biological contaminants
without an adverse effect on the biological material.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an object of the present invention to
provide methods of sterilizing biological materials by reducing the
level of active biological contaminants without adversely effecting
the biological material. Other objects, features and advantages of
the present invention will be set forth in the detailed description
of preferred embodiments that follows, and in part will be apparent
from the description or may be learned by practice of the
invention. These objects and advantages of the invention will be
realized and attained by the compositions and methods particularly
pointed out in the written description and claims hereof.
[0009] In accordance with these and other objects, a first
embodiment of the present invention is directed to a method for
sterilizing a biological material that is sensitive to ionizing
radiation comprising: (i) reducing the residual solvent content of
a biological material to a level effective to protect the
biological material from ionizing radiation; and (ii) irradiating
the biological material with radiation at an effective rate for a
time effective to sterilize the biological material.
[0010] A second embodiment of the present invention is directed to
a method for sterilizing a biological material that is sensitive to
ionizing radiation comprising: (i) adding to a biological material
at least one stabilizer in an amount effective to protect the
biological material from ionizing radiation; and (ii) irradiating
the biological material with radiation at an effective rate for a
time effective to sterilize the biological material.
[0011] A third embodiment of the present invention is directed to a
method for sterilizing a biological material that is sensitive to
ionizing radiation comprising: (i) reducing the residual solvent
content of a biological material to a level effective to protect
the biological material from ionizing radiation; (ii) adding to the
biological material at least one stabilizer in an amount effective
to protect the biological material from ionizing radiation; and
(iii) irradiating the biological material with radiation at an
effective rate for a time effective to sterilize the biological
material.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A. DEFINITIONS
[0012] Unless defined otherwise, all technical and scientific terms
used herein are intended to have the same meaning as is commonly
understood by one of ordinary skill in the relevant art. All
patents and publications mentioned herein are expressly
incorporated by reference.
[0013] As used herein, the term "biological material" is intended
to mean any substance derived or obtained from a living organism.
Illustrative examples of biological materials include, but are not
limited to, the following: cells; tissues; blood or blood
components; proteins, including recombinant and transgenic
proteins; botanicals; foods and the like. Preferred examples of
biological materials include, but are not limited to, the
following: ligaments; tendons; nerves; bone, including
demineralized bone matrix, grafts, joints, femurs, femoral heads,
etc.; teeth; skin grafts; bone marrow, including bone marrow cell
suspensions, whole or processed; heart valves; cartilage; corneas;
arteries and veins; organs for transplant, such as hearts, lungs,
liver, kidney, intestine, pancreas, limbs and digits; lipids;
carbohydrates; collagen (native, afibrillar, atelomeric, soluble
and insoluble); chitin and its derivatives including chitosan and
its derivatives including NO-carboxy chitosan (NOCC); stem cells,
islet of langerhans cells, and other cellular transplants,
including genetically altered cells; red blood cells; white blood
cells, including monocytes and stem cells; and platelets.
[0014] As used herein, the term "sterilize" is intended to mean a
reduction in the level of at least one active biological
contaminant found in the biological material being treated
according to the present invention.
[0015] As used herein, the term "biological contaminant" is
intended to mean a contaminant that, upon direct or indirect
contact with a biological material, may have a deleterious effect
on a biological material. Such biological contaminants include the
various viruses, bacteria and parasites known to those of skill in
the art to generally be found in or infect biological materials
such as whole blood or blood components. Examples of biological
contaminants include, but are not limited to, the following:
viruses, such as human immunodeficiency viruses and other
retroviruses, herpes viruses, paramyxoviruses, cytomegaloviruses,
hepatitis viruses (including hepatitis B and hepatitis C), pox
viruses, toga viruses, Ebstein-Barr virus and parvoviruses;
bacteria, such as Escherichia, Bacillus, Campylobacter,
Streptococcus and Staphalococcus; parasites, such as Trypanosoma
and malarial parasites, including Plasmodium species; yeasts;
molds; mycoplasmas; and prions. As used herein, the term "active
biological contaminant" is intended to mean a biological
contaminant that is capable of causing the deleterious effect.
[0016] As used herein, the term "blood components" is intended to
mean one or more of the components that may be separated from whole
blood and include, but are not limited to, cellular blood
components, such as red blood cells, white blood cells and
platelets; blood proteins, such as blood clotting factors, enzymes,
albumin, plasminogen, fibrinogen and immunoglobulins; and liquid
blood components, such as plasma and plasma-containing
compositions.
[0017] As used herein, the term "cellular blood component" is
intended to mean one or more of the components of whole blood that
comprises cells, such as red blood cells, white blood cells or
platelets.
[0018] As used herein, the term "blood protein" is intended to mean
one or more of the proteins that are normally found in whole blood.
Illustrative examples of blood proteins found in mammals (including
humans) include, but are not limited to, coagulation proteins (both
vitamin K-dependent, such as Factor VII or Factor IX, and
non-vitamin K-dependent, such as Factor VIII and von Willebrands
factor), albumin, lipoproteins (high density lipoproteins and/or
low density lipoproteins), complement proteins, globulins (such as
immunoglobulins IgA, IgM, IgG and IgE), and the like. A preferred
group of blood proteins include Factor I (Fibrinogen), Factor II
(Prothrombin), Factor III (Tissue Factor), Factor IV (Calcium),
Factor V (Proaccelerin), Factor VI (Accelerin), Factor VII
(Proconvertin, serum prothrombin conversion), Factor VIII
(Antihemophiliac factor A), Factor IX (Antihemophiliac factor B),
Factor X (Stuart-Prower Factor), Factor XI (Plasma thromboplastin
antecedent), Factor XII (Hageman Factor), Factor XIII
(Protansglutamidase), von Willebrand Factor (vWF), Factor Ia,
Factor IIa, Factor Va, Factor VIa, Factor VIIa, Factor VIIIa,
Factor IXa, Factor Xa, and Factor XIIIa.
[0019] As used herein, the term "liquid blood component" is
intended to mean one or more of the fluid, non-cellular components
of whole blood, such as plasma (the fluid, non-cellular portion of
the blood of humans or animals as found prior to coagulation) or
serum (the fluid, non-cellular portion of the blood of humans or
animals after coagulation).
[0020] As used herein, the term "a biologically compatible
solution" is intended to mean a solution to which biological
materials may be exposed, such as by being suspended or dissolved
therein, and remain viable, i.e., retain their essential biological
and physiological characteristics. Such biologically compatible
solutions preferably contain an effective amount of at least one
anticoagulant.
[0021] As used herein, the term "a biologically compatible buffered
solution" is intended to mean a biologically compatible solution
having a pH and osmotic properties (e.g., tonicity, osmolality
and/or oncotic pressure) suitable for maintaining the integrity of
biological materials. Suitable biologically compatible buffered
solutions typically have a pH between 5 and 8.5 and are isotonic or
only moderately hypotonic or hypertonic. Biologically compatible
buffered solutions are known and readily available to those of
skill in the art.
[0022] As used herein, the term "stabilizer" is intended to mean a
compound or material that reduces any damage to the biological
material being irradiated to a level that is insufficient to
preclude the safe and effective use of that material. Illustrative
examples of stabilizers include, but are not limited to, the
following: antioxidants, such as ascorbic acid and tocopherol; and
free radical scavengers, such as ethanol, including Type I and Type
II free radical scavengers, preferably at least one Type I and at
least one Type II free radical scavenger. Preferred examples of
stabilizers include, but are not limited to, the following: fatty
acids, including 6,8-dimercapto-octanoic acid (lipoic acid) and its
derivatives and analogues (alpha, beta, dihydro, bisno and tetranor
lipoic acid), thioctic acid, 6,8-dimercapto-octanoic acid,
dihydrolopoate(DL-6,8-dithioloctanoic acid methyl ester),
lipoamide, bisonor methyl ester and tatranor-dihydrolipoic acid,
furan fatty acids, oleic and linoleic and palmitic acids and their
salts and derivatives; flavonoids, phenylpropaniods, and flavenols,
such as quercetin, rutin and its derivatives, apigenin,
aminoflavone, catechin, hesperidin and, naringin; carotenes,
including beta-carotene; Co-Q10; xanthophylls; polyhydric alcohols,
such as glycerol, mannitol; sugars, such as xylose, glucose,
ribose, mannose, fructose and trehalose; amino acids, such as
histidine, N-acetylcysteine (NAC), glutamic acid, tryptophan,
sodium carpryl N-acetyl tryptophan and methionine; azides, such as
sodium azide; enzymes, such as Superoxide Dismutase (SOD) and
Catalase; uric acid and its derivatives, such as 1,3-dimethyluric
acid and dimethylthiourea; allopurinol; thiols, such as glutathione
and cysteine; trace elements, such as selenium; vitamins, such as
vitamin A, vitamin C (including its derivatives and salts such as
sodium ascorbate and palmitoyl ascorbic acid) and vitamin E (and
its derivatives and salts such as tocopherol acetate and
alpha-tocotrienol); chromanol-alpha-C6;
6-hydroxy-2,5,7,8-tetramethylchroma-2 carboxylic acid (Trolox) and
derivatives; extraneous proteins, such as gelatin and albumin;
tris-3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186); citiolone;
puercetin; chrysin; dimethyl sulfoxide (DMSO); piperazine
diethanesulfonic acid (PIPES); imidazole; methoxypsoralen (MOPS);
1,2-dithiane-4,5-diol; reducing substances, such as butylated
hydroxyanisole (BHA) and butylated hydroxytoluene (BHT);
cholesterol; probucol; indole derivatives; thimerosal; lazaroid and
tirilazad mesylate; proanthenols; proanthocyanidins; ammonium
sulfate; Pegorgotein (PEG-SOD); N-tert-butyl-alpha-phenylnitrone
(PBN); and 4-nydroxy-2,2,6,6-Tetramethylpiperidin-1-oxyl
(Tempol).
[0023] As used herein, the term "residual solvent content" is
intended to mean the amount of freely-available liquid in the
biological material. Freely-available liquid means that liquid,
such as water or an organic solvent (e.g. ethanol, isopropanol,
polyethylene glycol, etc.), present in the biological material that
is not bound to or complexed with one or more of the non-liquid
components of the biological material (e.g. proteins, metal ions or
salts, etc.). Freely-available liquid includes intracellular water.
The residual solvent contents referenced herein refer to levels
determined by the FDA approved, modified Karl Fischer method (Meyer
and Boyd, Analytical Chem., 31, 215-219, 1959; May, et al., J.
Biol. Standardization, 10, 249-259, 1982; Centers for Biologics
Evaluation and Research, FDA, Docket No. 89D-0140, 83-93;
1990).
[0024] As used herein, the term "sensitizer" is intended to mean a
substance that selectively targets viral, bacterial, and/or
parasitic contaminants, rendering them more sensitive to
inactivation by radiation, therefore permitting the use of a lower
rate of radiation and/or a shorter time of irradiation than in the
absence of the sensitizer. Illustrative examples of suitable
sensitizers include, but are not limited to, the following:
psoralen and its derivatives and analogs (including 3-carboethoxy
psoralens); angelicins, khellins and coumarins which contain a
halogen substituent and a water solubilization moiety, such as
quaternary ammonium ion or phosphonium ion; nucleic acid binding
compounds; brominated hematoporphyrin; phthalocyanines; purpurins;
porphorins; halogenated or metal atom-substituted derivatives of
dihematoporphyrin esters, hematoporphyrin derivatives,
benzoporphyrin derivatives, hydrodibenzoporphyrin dimaleimade,
hydrodibenzoporphyrin, dicyano disulfone, tetracarbethoxy
hydrodibenzoporphyrin, and tetracarbethoxy hydrodibenzoporphyrin
dipropionamide; doxorubicin and daunomycin, which may be modified
with halogens or metal atoms; netropsin; BD peptide, S2 peptide;
S-303 (ALE compound); dyes, such as hypericin, methylene blue,
eosin, fluoresceins (and their derivatives), flavins, merocyanine
540; photoactive compounds, such as bergapten; and SE peptide.
[0025] As used herein, the term "proteinaceous material" is
intended to mean a cellular material that comprises at least one
protein or peptide. This material is preferably composed primarily
of protein(s) and/or peptide(s). It may be a naturally occurring
material, either in its native state or following
processing/purification and/or derivatization. It may be
artificially produced, either by chemical synthesis or utilizing
recombinant/transgenic technology. Such artificially produced
material may also be processed/purified and/or derivatized.
Illustrative examples of proteinaceous materials include, but are
not limited to, the following: proteins/peptides produced from
tissue culture; milk (dairy products); ascites; hormones; growth
factors; materials, including pharmaceuticals, extracted or
isolated from animal tissue (such as heparin and insulin) or plant
matter; plasma (including fresh, frozen and freeze-dried);
fibrinogen, fibrinogen derivatives, fibrin, fibrin I, fibrin II,
soluble fibrin and fibrin monomer, and/or fibrin sealant products;
whole blood; protein C; protein S; alpha-1anti-trypsin (alpha-1
protease inhibitor); butyl-cholinesterase; anticoagulants, such as
coumarin drugs (warfarin); streptokinase; tissue plasminogen
activator (TPA); erythropoietin (EPO); urokinase; neupogen;
anti-thrombin-3; alpha-glucosidase; (Fetal) Bovine Serum/Horse
Serum; meat; immunoglobulins, including anti-sera, monoclonal
antibodies, polyclonal antibodies and genetically engineered or
produced antibodies; albumin; alpha-globulins; beta-globulins;
gamma-globulins; coagulation proteins; complement proteins; and
interferons.
[0026] As used herein, the term "ionizing radiation" is intended to
mean radiation of sufficient energy to ionize (produce ions) the
irradiated biological material. Types of ionizing radiation
include, but are not limited to, the following: (i) corpuscular
(streams of subatomic particles such as neutrons, electrons
(including e-beam radiation), and/or protons); and (ii)
electromagnetic (originating in a varying electromagnetic field,
such as radio waves, visible and invisible light (including
ultraviolet), x-radiation, and gamma rays).
B. PARTICULARLY PREFERRED EMBODIMENTS
[0027] A first preferred embodiment of the present invention is
directed to a method for sterilizing a biological material that is
sensitive to ionizing radiation comprising: (i) reducing the
residual solvent content of a biological material to a level
effective to protect the biological material from ionizing
radiation; and (ii) irradiating the biological material with
radiation at an effective rate for a time effective to sterilize
the biological material.
[0028] A second embodiment of the present invention is directed to
a method for sterilizing a biological material that is sensitive to
ionizing radiation comprising:
[0029] (i) adding to a biological material at least one stabilizer
in an amount effective to protect the biological material from
ionizing radiation; and (ii) irradiating the biological material
with radiation at an effective rate for a time effective to
sterilize the biological material.
[0030] A third embodiment of the present invention is directed to a
method for sterilizing a biological material that is sensitive to
ionizing radiation comprising: (i) reducing the residual solvent
content of a biological material to a level effective to protect
the biological material from ionizing radiation; (ii) adding to the
biological material at least one stabilizer in an amount effective
to protect the biological material from ionizing radiation; and
(iii) irradiating the biological material with radiation at an
effective rate for a time effective to sterilize the biological
material. The order of steps (i) and (ii) may, of course, be
reversed as desired.
[0031] The biological material sterilized in accordance with the
methods of the present invention may be any material obtained or
derived from a living or deceased organism, including a solid
material or liquid material or a suspension of any solid(s) in any
liquid(s) or a coating of any solid or liquid on a biological or
non-biological substrate.
[0032] According to the methods of the present invention, the
residual solvent content of the biological material is reduced
prior to irradiation of the biological material with ionizing
radiation. The residual solvent content is reduced to a level that
is effective to protect the biological material from the ionizing
radiation. Suitable levels of residual solvent content may vary
depending upon the nature and characteristics of the particular
biological material being irradiated and can be determined
empirically by one skilled in the art. Preferably, when the solvent
is water, the residual solvent content is less than about 2.0%,
more preferably less than about 1.0%, even more preferably less
than about 0.5% and most preferably less than about 0.2%.
[0033] While not wishing to be bound by any theory of operability,
it is believed that the reduction in residual solvent content
reduce the degrees of freedom of the biological material and
thereby protects it from the effects of the ionizing radiation.
Similar results might therefore be achieved by lowering the
temperature of the biological material below its eutectic point or
below its freezing point to likewise reduce the degrees of freedom
of the biological material. These results permit the use of a
higher rate of irradation than might otherwise be acceptable.
[0034] The residual solvent content of the biological material may
be reduced by any of the methods and techniques known to those
skilled in the art for removing solvent from a biological material.
A particularly preferred method for reducing the residual solvent
content of a biological material is lyophilization. According to a
particularly preferred embodiment of the present invention, a
biological material which has been lyophilized is stored under
vacuum or an inert atmosphere (preferably a noble gas, such as
helium or argon, more preferably a higher molecular weight noble
gas, and most preferably argon) prior to irradation.
[0035] The ionizing radiation employed in the present invention may
be any ionizing radiation effective for the inactivation of one or
more biological contaminants of the biological material being
treated. Preferably the ionizing radiation is electromagnetic
radiation and a particularly preferred form of ionizing radiation
is gamma radiation.
[0036] According to the methods of the present invention, the
biological material is irradiated with the ionizing radiation at a
rate effective for the inactivation of one or more biological
contaminants of the biological material. Suitable rates of
irradiation may vary depending upon the particular form of ionizing
radiation and the nature and characteristics of the particular
biological material being irradiated and the particular biological
contaminants being inactivated. Suitable rates of irradiation can
be determined empirically by one skilled in the art. Preferably,
the rate of irradiation is constant for the duration of the
sterilization procedure.
[0037] According to a particularly preferred embodiment of the
present invention, the rate of irradiation is not more than about
3.0 kGy/hour, more preferably between about 0.1 kGy/hr. and 3.0
kGy/hr, even more preferably between about 0.25 kGy/hr and 2.0
kGy/hour, still even more preferably between about 0.5 kGy/hr and
1.5 kGy/hr and most preferably between about 0.5 kGy/hr and 1.0
kGy/hr.
[0038] According to another particularly preferred embodiment of
the present invention, the rate of irradiation is at least about
3.0 kGy/hr., more preferably at least about 6 kGy/hr., even more
preferably at least about 16 kGy/hr., and most preferably at least
about 30 kGy/hr.
[0039] The biological material is irradiated with the ionizing
radiation for a time effective for the inactivation of one or more
biological contaminants of the biological material. Suitable
irradiation times may vary depending upon the particular form and
rate of ionizing radiation and the nature and characteristics of
the particular biological material being irradiated and the
particular biological contaminants being inactivated. Suitable
irradiation times can be determined empirically by one skilled in
the art.
[0040] Optionally, an effective amount of at least one sensitizer
is added to the biological material prior to irradiation with
ionizing radiation. Suitable sensitizers are known to those skilled
in the art.
[0041] According to methods of the present invention, the
irradiation of the biological material may occur at any temperature
which is not deleterious to the biological material being treated.
According to a preferred embodiment, the biological material is
irradiated at ambient temperature. According to an alternate
preferred embodiment, the biological material is irradiated at
reduced temperature, preferably at or below the eutectic point of
the biological material.
C. EXAMPLES
[0042] The following examples are illustrative, but not limiting,
of the present invention. Other suitable modifications and
adaptations are of the variety normally encountered by those
skilled in the art and are fully within the spirit and scope of the
present invention.
Example 1
Sterilization of Blood
[0043] A 200 ml bag of one day old packed red blood cells was used.
Ethanol was added to the cells in order to achieve a final ethanol
concentration of 0.01% v/v. The red blood cells were diluted by a
factor of one in ten using a modified Citrate Phosphate Dextrose
(CPD) solution having a pH of about 6.4 to 6.7 and having the
following composition in a total volume of 500 ml:
TABLE-US-00001 Citrate Acid Monohydrate 0.2 g Sodium Citrate
Dihydrate 27.3 g Sodium Monobasic Phosphate 2.2 g Sodium Dibasic
Phosphate 1.0 g Dextrose 3.2 g
[0044] The cells were irradiated in a commercial size gamma
irradiator which contained a cobalt 60 source rack. Irradiation was
done off carrier in an unprotected box. The cells were irradiated
for twenty-four hours at a rate of approximately 1 kGy/hr. After
the irradiation period the red blood cells were examined visually
and were found to be viable, having a brilliant red color. A
control sample, consisting of packed red blood cells that were not
diluted with the above-described CPD solution, was not viable after
irradiation.
[0045] Four days after the irradiation procedure, the diluted cells
were tested for levels of various blood components and the results
are shown in Table 1. The control sample consisted of blood from
the same bag as the test sample but it did not undergo irradiation.
Table 1 illustrates that dilution and irradiation of human blood
cells did not significantly alter the white blood cell count. The
platelet count and hematocrit values were slightly lower than the
control; however, these values are still within the range that is
seen in normal adult blood. The level of hemoglobin was higher than
in the control indicating that some red blood cells did lyse during
the procedure. This is also evidenced by the lower red blood cell
count. Nevertheless, contrary to what has been previously
published, up to 50 kGy of radiation did not destroy the components
of blood by the present procedure. The cells were also counted and
found to be viable after 25 kGy of gamma irradiation delivered at a
low dose rate of 1 kGy/hr.
TABLE-US-00002 TABLE 1 Component Irradiated Blood Control Blood
White Blood Cells 4 K/mm.sup.3 4.8 K/mm.sup.3 Red Blood Cells 3
Mi/mm.sup.3 7.2 Mi/mm.sup.3 Hemoglobin 42 g/dl 21 g/dl Hematocrit
46% 64% Platelet 100 k/mm.sup.3 120 k/mm.sup.3
Example 2
Sterilization of Dextrose
[0046] Dextrose (or glucose) containing solutions are used in the
treatment of carbohydrate and fluid depletion, in the treatment of
hypoglycemia, as a plasma expander, in renal dialysis and to
counteract hepatotoxins (The Merck Index, Eleventh Edition, Merck
& Co., Inc. (1989), and Martindale's Extra Pharmacopecia, p. 1,
265). Dextrose is also the preferred source of carbohydrate in
parental nutrition regiments (The Merck Index, Eleventh Edition,
Merck & Co., Inc. (1989), and Martindale's Extra Pharmacopecia,
p. 1, 265). In all of the above applications, the dextrose must be
sterilized before use. Sterilization of dextrose-containing
products is generally done by heat sterilization or autoclaving.
Unfortunately, these methods have been reported to degrade or
carmelize dextrose-containing solutions resulting in a color change
in the solution (Martindale's Extra Pharmacopecia, p. 1, 265).
Gamma irradiation of glucose has also been reported to decompose
glucose-containing solutions (Kawakishi, et al., "Radiation-Induced
Degradation of D-glucose in Anaerobic Contition," Agric. Biol.
Chem., June 1977). Therefore, there is a need for a method that can
sterilize dextrose-containing products that does not degrade the
product itself. In view of the problems of the prior art, a
dextrose solution was treated according to the method of the
present invention as follows.
[0047] A 5% dextrose solution was irradiated for 24 hours, at a
rate of approximately 1 kGy/hr. After irradiation, the product was
tested and it was found that there was no visible light spectrum
change as compared to the non-irradiated control. Therefore, the
present method can be useful in sterilizing products that contain
dextrose.
[0048] In addition to the above experiment, fresh solutions of 5%
and 50% dextrose were irradiated to 25 kGy over 36 hours at ambient
temperature. The results were similar to those described above. In
addition, UV/VIS scans were obtained and demonstrated a complete
absence of the peak at 283.4 nm for "furfural" as per U.S.P. In
contrast, dextrose samples sterilized using an autoclave contain
the 283.4 furfural peak. "Furfurals" are carcinogenic.
Example 3
Sterilization of Human Serum Albumin
[0049] Normal Human Serum Albumin was irradiated as a 25% salt-poor
solution to a total dose of 25 kGy over 36 hours using a Gammacell
220 (Co.sup.60 is the gamma ray source in this instrument). The
temperature was not controlled during the irradiation but it is
estimated that the container holding the albumin solution was
approximately 23.degree. C. The results of HPLC analysis are given
in Table 2.
TABLE-US-00003 TABLE 2 Parameter Control (%) Irradiated (%) Polymer
2 3 Dimer 7 8 Monomer 90 86 Low Molecular Weight 1 3 pH 7.05 6.97
NTU (must be >20) 11.4 11.4
[0050] As the results demonstrate, Normal Human Serum Albumin can
safely be irradiated to 25 kGy (at a rate of approximately 0.7
kGy/hr) at room temperature without adversely affecting the
essential properties of the protein. This has not been demonstrated
before. All other attempts at irradiating serum albumin require
that it be irradiated in the frozen stage. This adds to the cost
and difficulty of doing the irradiation.
Example 4
[0051] Normal human blood from a healthy donor was taken in a
heparinized tube, washed three times with standard CPD solution,
then diluted 1:20 with CPD containing 0.01% v/v Ethanol. This
latter solution of CPD with 0.01% v/v Ethanol is called SCPD. Two
ml aliquots were then placed in 10 ml plastic test tubes and
irradiated to different doses up to 26 kGy over 36 hours at room
temperature. There was no haemolysis and the cells appeared intact
if somewhat large and slightly irregular in shape. The results of
three separate experiments are reported in Table 3.
TABLE-US-00004 TABLE 3 Parameter RCB.sup.1 HGB.sup.2 HCT.sup.3
MCV.sup.4 MCH.sup.5 MCHC.sup.6 RDW.sup.7 Flags 1* 1.08 41 .097 89.5
38.3 427 17.7 Nearly Control .99 33 0.89 90.2 33.0 366 15.3 Normal
2* 95.0 32.3 339 12.0 12 kGy 1 1.22 45 .166 135.8 36.5 269 27.3 1 +
Anisocytosis 1.38 45 .199 144.7 33.0 228 24.9 3 + Macrocytocis 1
1.04 32 .169 163.0 31.3 152 18.8 1 + Anisocytosis 16 kGy 0.54 29
.088 162.5 54.5 335 18.8 3 + Macrocytocis 2 0.82 27 .128 156.5 32.8
209 19.8 2 + Anisocytosis 0.81 26 .124 152.6 32.4 212 20.2 3 +
Macrocytocis 1 0.79 244 .125 158.4 30.8 194 19.4 1 + Anisocytosis
20 kGy 1.26 28 .203 161.5 22.1 137 19.0 3 + Macrocytocis 2 0.93 30
.141 151.5 32.3 213 20.1 2 + Anisocytosis 0.92 30 .143 155.5 32.1
207 20.5 3 + Macrocytocis 26 kGy 1 1.15 34 .180 155.9 29.4 189 19.1
1 + Anisocytosis 1.15 34 .176 153.0 29.9 195 23.4 3 + Macrocytocis
*Experiment 1 and Experiment 2 .sup.1Red Blood Cell Count: Cells
.times. 10.sup.12/liter .sup.2Hemoglobin: grams/liter
.sup.3Hematocrit .sup.4Mean Corpuscular Volume: Femtoliters
.sup.5Mean Corpuscular Hemoglobin: picograms .sup.6Mean Corpuscular
Hemoglobin Concentration: grams/liter
[0052] The cells were easily put into suspension and reconstituted
in fresh buffer.
[0053] The following three experiments (Examples 5, 6 and 7) were
conducted in order to determine the efficacy of the method when
treating HIV-contaminated blood. In each Example the cells were
similarly treated. In these experiments, the cells were gently
agitated after 12, 16 and 24 hours of irradiation. Further, in the
third experiment (Example 7), the cells were placed in T25 flasks
to provide greater surface area and reduce the concentration due to
settling in the bottom of the centrifuge tubes. In each case, the
cells were irradiated at a dose rate of approximately 0.7
kGy/hr.
Example 5
Sterilization of HIV-Containing Blood
[0054] The following experiments were undertaken with the following
specific objectives: [0055] 1. To evaluate the toxicity of the
process towards red blood cells (RBCs). [0056] 2. To evaluate the
anti-retroviral activity of the process.
Procedure
[0057] Initially, 2 ml of anticoagulated blood was obtained from an
HIV-seronegative donor. The blood was centrifuged, and the plasma
was removed. The remaining cell pellet was resuspended in 10 ml of
the CPD buffer and centrifuged. This washing process was repeated a
total of three times. The final pellet was resuspended in 40 ml of
the SCPD buffer, and distributed into plastic tubes in 2 ml
aliquots, with 16 separate aliquots being retained for further
manipulation. For 8 of these tubes, an aliquote of HTLV-IIIB was
added. This is a laboratory strain of the HIV virus and 100 tissue
culture infective doses (TCID) were added to each of the tubes to
be infected. For the remaining 8 tubes, a "mock" infection was
performed, by adding a small amount of non-infectious laboratory
buffer, phosphate buffered saline (PBS). Four infected and four
non-infected tubes were subjected to the process. For comparison,
the remaining 8 tubes (four infected and four non-infected) were
handled in an identical manner, except that they were not subjected
to the process.
[0058] It should be stated that at the beginning of the study, a
separate aliquot of blood was obtained from the donor. This was
processed in the clinical hematology laboratory and a complete
hemogram was performed. These baseline results were compared to
repeat testing on the study aliquots, which included evaluation of
four processed and four unprocessed samples, all of which were not
infected with HIV.
[0059] An aliquot of 0.5 ml of each of the infected study samples
was inoculated on mononuclear cells (MCs) which had been obtained
three days earlier. These cells had been suspended in RMPI culture
medium, with 10% fetal calf serum and other additives (penicillin,
streptomycin, glutamine and HEPES buffer) along with 1 .mu.g/ml
PHA-P. At the same time as this inocculation, the cells were
resuspended in fresh medium with rIL-2 (20 U/ml). The cultures were
maintained for 7 days. Twice weekly, a portion of the culture
medium was harvested for the measurement of HIV p24 antigen levels
(commercial ELISA kit, Coulter Electronics, Hialeah, Fla.) for the
measurement of viral growth.
[0060] A separate aliquot of the eight infected study samples was
used for viral titration experiments. Briefly, serial four-fold
dilutions of the virus-containing fluids (ranging from 1:16 to
1:65,536) were inoculated in triplicate in 96-well flat-bottom
tissue culture plates. PHA-stimulated MCs were added to each well
(4 million cells in 2 ml culture medium, with IL-2). An aliquot of
the supernatant from each culture well was harvested twice weekly
for the measurement of HIV p24 antigen levels. A well was scored as
"positive" if the HIV p24 antigen value was >30 pg/ml.
[0061] The viral titer was calculated according to the
Spearman-Karber method (se ACTG virology protocol manual) using the
following equation:
M=xk+d[0.5-(1/n)r] [0062] M: titer (in log 4) [0063] xk: dose of
highest dilution [0064] d: space between dilutions [0065] n: number
of wells per dilution [0066] r: sum of total number of wells.
Results
[0067] Red blood cell parameters for the baseline sample as well as
for the unprocessed and processed study samples are shown in Table
4.
TABLE-US-00005 TABLE 4 Sample/Number MCV MCH MCHC Baseline 94.5
32.0 339 Unprocessed-1 91.4 34.4 376 Unprocessed-2 90.2 37.9 420
Unprocessed-3 92.1 40.0 433 Unprocessed-4 91.0 40.2 442 Processed-1
133.4 37.8 284 Processed-2 131.5 45.0 342 Processed-3 128.5 38.9
303 Processed-4 131.1 39.4 301
[0068] The abbreviations in Table 4 are explained under Table
3.
[0069] As described above, HIV cultures were established using 0.5
ml aliquots of unprocessed and processed study samples. P24 antigen
levels (pg/ml) from the study samples on day 4 and day 7 of culture
are shown in Table 5.
TABLE-US-00006 TABLE 5 p24 p24 Sample/Number Day 4 Day 7
Unprocessed-1 1360 484 Unprocessed-2 1180 418 Unprocessed-3 1230
516 Unprocessed-4 1080 563 Processed-1 579 241 Processed-2 760 303
Processed-3 590 276 Processed-4 622 203
[0070] Finally, one unprocessed sample and one processed sample
were selected for the performance of direct viral titration without
culture. The results are shown in Table 6.
TABLE-US-00007 TABLE 6 Sample/Number Titer (log 10 ml)
Unprocessed-1 1.5 Processed-1 0.0
[0071] The red blood cells were minimally affected by the process,
although some reproducible macrocytosis was observed. Although on
co-culturing of processed samples, there appeared to be some
residual live virus, this was not confirmed by direct titration
experiments.
Example 6
[0072] The objective of this experiment was to evaluate the
toxicity of the process towards red blood cells in a comprehensive
manner.
Methods
[0073] For this experiment, 1 ml of anticoagulated blood was
obtained from the same HIV-seronegative donor as in the first
experiment. The blood was centrifuged and the plasma was removed.
The remaining cell pellet was resuspended in 10 ml of the CPD
buffer and centrifuged. This washing process was repeated a total
of three times. The final pellet was resuspended in 20 ml of the
SCPD buffer and distributed into plastic tubes in 2 ml aliquots
with all 10 aliquots being retained for further manipulation. Eight
tubes were subjected to the process, while the final two tubes were
retained as control, unprocessed tubes. After the processing, all
the tubes were centrifuged, and the resulting pellet was
resuspended in 100 .mu.l buffer. A complete hemogram was performed
on these reconcentrated study samples.
[0074] As in the first experiment, a separate aliquot of blood was
obtained from the donor when the study sample was taken. A complete
hemogram was performed on this baseline sample. As the study
samples were re-concentrated to 33-50% of their original state,
more direct comparisons with the baseline sample could be
undertaken than were possible in our earlier experiment.
Results
[0075] Red blood cell parameters for the baseline sample as well as
for the unprocessed and processed study samples are shown in Table
7. The abbreviations used in Table 7 are defined in Table 3.
TABLE-US-00008 TABLE 7 Sample/ Number RBC HGS MCV MCH MCHC Baseline
4.76 152 94.9 31.9 336 Unprocessed-1 0.99 33 90.2 33.0 366
Unprocessed-2 1.08 41 89.5 38.3 427 Processed-1 1.15 34 153.0 29.9
195 Processed-2 1.15 34 155.9 29.4 189 Processed-3 1.26 28 161.5
22.1 137 Processed-4 0.79 24 158.4 30.8 194 Processed-5 0.54 29
162.5 54.5 335 Processed-6 1.04 32 163.0 31.3 192 Processed-7 1.35
45 144.7 33.0 228 Processed-8 1.22 45 135.8 36.5 269
[0076] There was macrocytosis of the cells which was present in all
the processed samples. Comparable hemoglobin levels were measured
in the unprocessed and processed samples. The absolute values were
appropriate for the residual dilution. The red blood cells are
preserved.
Example 7
Methods
[0077] For this experiment, 5 ml of anticoagulated blood was
obtained from the same HIV-seronegative donor as in the first two
experiments. The blood was centrifuged, and the plasma was removed.
The remaining cell pellet was resuspended in 100 ml of the CPD
buffer, and centrifuged. This washing process was repeated a total
of three times. The final pellet was resuspended in 100 ml of the
SCPD buffer and distributed in 25 ml aliquots, in T25 tissue
culture flasks, with all four aliquots being retained for further
manipulation. Two flakes were subject to the process, while the
other two were retained as control, unprocessed flasks. After the
processing, the contents of each of the flasks was observed and a
visual determination of the cells' capacity to absorb oxygen
(turning a brighter red on exposure to ambient air) was made.
Following this, the contents of the flasks were aspirated and
centrifuged, with the residual pallet resuspended in a small volume
of buffer. A complete hemogram was performed on these
re-concentrated study samples.
[0078] As in Examples 5 and 6, a separate aliquot of blood was
obtained from the donor when the study sample was taken. A complete
hemogram was performed on this baseline sample. As the study
samples were re-concentrated to 33-50% of their original state,
direct comparisons of a number of specific parameters would be
possible with the baseline sample.
Results
[0079] On visual inspection, there were no appreciable differences
between the processed and unprocessed study samples. Specifically,
there appeared to be a uniform distribution of well suspended
cells. On exposure to ambient air, the contents of all flasks
became somewhat brighter red. No specific quantitative measurements
of oxygenation were made.
[0080] Red blood cell parameters for the baseline sample as well as
for the unprocessed and processed study samples are shown in Table
8. The abbreviations used in Table 8 are defined under Table 3.
TABLE-US-00009 TABLE 8 Sample/ Number RBC HGS MCV MCH MCHC Baseline
4.75 153 95.0 32.3 339 Unprocessed-1 0.93 30 151.5 32.3 213
Unprocessed-2 0.92 30 155.5 32.1 207 Processed-1 0.82 27 156.5 32.8
209 Processed-2 0.81 26 152.6 32.4 212
[0081] This experiment was designed to more closely approximate
conditions of red blood cells to be transfused into a patient, and
was consequently conducted at higher volumes. On a preliminary
basis, it does not appear that the process impairs the red blood
cells' ability to carry oxygen, although this should be measured
more formally. Interestingly, in this experiment, there was no
difference in cell size between the processed and unprocessed
samples, both being large compared to baseline. Comparable
hemoglobin levels were measured in all the study samples.
Example 8
[0082] In this experiment, Immunoglobulin G (IgG) was irradiated in
lyophilized form.
Method
[0083] The results of HPLC analysis of IgG are given in Table 9. As
the results demonstrate, the product appears to be unaffected after
being irradiated to a dose of 25 kGy at room temperature when the
irradiation is delivered at a rate of approximately 0.7 kGy/hr.
This has not been previously demonstrated.
TABLE-US-00010 TABLE 9 Parameter Control (%) Irradiated (%) Polymer
(must be >2%) 1 1 Dimer 10 13 Monomer 88 84 Low Molecular Weight
1 2
[0084] The results presented by Gergely, et al., using freeze dried
IgG showed that a portion of the protein was insoluble after an
irradiation dose of 12 kGy to 25 kGy at standard irradiation dose
rates. (Gergely, J., et al., "Studies of Gama-Ray-Irradiated Human
Immunoglobulin G." SM-92/12 I.A.E.A.) In contrast, using the
present method at a dose rate of approximately 0.7 kGy/hr, none of
the protein was insoluble. This would indicate that little or no
change or degradation of the protein occurred. Further, Gergely, et
al., found that a liquid formulation of human IgG lost all of its
activity after irradiation. In studies using the present method on
intravenous immunoglobulin (IVIG) in liquid form, it was shown that
greater than 70% of a specific antibody in hyperimmune IVIG was
retained.
Example 9
[0085] In this experiment, alpha 1 proteinase inhibitor and
fibrinogen were irradiated in lyophilized form.
Method
[0086] The samples were placed in a Gammacell 220 and irradiated
according to the present process to a total dose of 25 kGy. Samples
were then returned to the laboratory for analysis. The dose rate
was 0.72 kGy/hr.
Results
[0087] The alpha 1 proteinase inhibitor, both treated and control,
were 40% of a standard normal pooled plasma sample. The Mancini
radial immunodiffusion technique was used as the assay.
[0088] The topical fibrinogen complex vials were reconstituted in
10 ml of water. Protamine sulphate vials were reconstituted in 10
ml of water. Protamine sulphate at a concentration of 10 mg/ml was
added to the samples. There was instant formation of monomer in all
three preparations.
Example 10
[0089] In this experiment, Factors VII, VIII and IV were irradiated
in lyophilized form.
Method
[0090] The samples were placed in a Gamacell 220 and irradiated to
various total doses at a dose rate of approximately 1 kGy/hr.
Results
[0091] Factor VII retained 67% activity at 20 kGy and 75% at 10
kGy. Factor VIII retained 77% activity at 20 kGy and 88% at 10 kGy.
Similarly, Factor IV showed an activity level of 70% at 20 kGy and
80% at 10 kGy.
Analysis
[0092] Excellent results were found for the three Factors. To our
knowledge, no one has been able to achieve these results by
irradiating the Factors at ambient temperature to such a high dose
of radiation with such little loss of activity. This is in direct
contrast with the results of Kitchen, et al, "Effect of Gamma
Irradiation on the Human Immunodeficiency Virus and Human
Coagulation Proteins," Vox Sang 56:223-229 (1989), who found that
"the irradiation of lyophilized concentrates is not a viable
procedure." Similarly, Hiemstra, et al., "Inactivation of human
immunodeficiency virus by gamma radiation and its effect on plasma
and coagulation factors," Transfusion 31:32-39 (1991), also
concluded that "Gamma radiation must be disregarded as a method for
the sterilization of plasma and plasma-derived products, because of
the low reduction of virus infectivity at radiation doses that
still give acceptable recovery of biologic activity of plasma
components."
Example 11
[0093] In this experiment, red blood cells were irradiated at a
dose rate of 0.5 kGy/hr for periods of time ranging from 7.5 to 90
minutes in order to remove bacterial contaminants.
Method
[0094] Red blood cells were collected from a healthy donor in EDTA,
washed 3 times with CPD solution and resuspended in DPC to provide
a 1:20 dilution based on the original blood volume. The cell
suspension was then subdivided into 14 tubes. To seven of the
tubes, approximately 1.0.times.10.sup.4 Staphylococcus epidermidia
were added. The cells were placed on ice for transport to the
irradiation facility. All of the samples were placed in the chamber
at ambient temperature and irradiated at 0.5 kGy/hr for periods of
time to give total doses of 0.625, 0.125, 0.250, 0.375, 0.500 and
0.750 kGy, respectively. The samples were removed and agitated at
each time point and placed on ice for transport either to the
microbiology lab or the hematology lab for analysis.
Results
[0095] The results of the microbiology assays are given in Table
10.
TABLE-US-00011 TABLE 10 Radiation Dose (kGy) Time (Min.) Number
Surviving 0 92,200 0.625 7.5 84,500 0.125 15 35,000 0.250 30 10,067
0.375 45 1,800 0.500 60 250 0.750 90 0
[0096] Thus, a dose of 0.75 kGy provides a 4.5 log.sub.10 reduction
in bacterial survivors. This represents a significant safety factor
for blood. Further, the D10 value is approximately 0.125 kGy which
corresponds well with the values reported in the literature for
similar species of staphylococcus (B. A. Bridges, "The effect of
N-Ethylmaleimide on the radiation sensitivity of bacteria," J Gen.
Microbiol. 26:467-472 (1962), and Jacobs, G. P. and Sadeh, N.,
"Radiosensitization of Staphyloccocus aureus by p-hydroxybenzoic
acid," Int. J. Radiat. Biol. 41:351-356 (1982).
[0097] In order to demonstrate that the red blood cells remained
viable after the irradiation process, the following parameters were
determined for the cells, WBC, Neutrophils, Lymphocytes, Monocytes,
Eosinophils and Basophils. These determinations merely enumerated
the number of cells present. All nucleated cells would, of course,
be inactivated by the radiation dose delivered. The other red blood
cell parameters monitored are listed in Table 11. The
Methaemoglobin value was unchanged from that of the controls even
after a radiation dose of 0.75 kGy. This experiment demonstrates
that red blood cells can be safely irradiated by the present method
to a dose of 0.75 kGy at room temperature with no loss of cell
function.
Example 12
[0098] This experiment was conducted using the method in Example 11
to confirm the findings of Example 11 and to expand upon some of
the parameters measured. The results of this experiment are given
in Table 12.
Results
[0099] (See Table 12, below.)
[0100] These results confirm the previous results and indicate that
indeed, red blood cells can be irradiated to a dose sufficient to
provide 4.5 log.sub.10 reduction in bacterial count.
[0101] It is contemplated that future experiments will provide
similar results for platelet. Thus, with little or no additional
manipulation, and without the addition of extraneous materials, red
blood cells can be treated by the present process to provide a
bacteriologically safe product, thus further reducing the risk of
untoward reactions in recipients.
TABLE-US-00012 TABLE 11 Red Blood Cell Valus as a Function of
Radiation Dose Received Total Dose (in kGy) Parameter Whole Blood 0
0.625 0.125 0.250 0.500 RBC 5.06 1.49 1.27 1.77 1.73 1.43 HGB 153
43 41 56 56 46 HTC .483 .142 .120 .156 .163 1.31 MCV 95.5 95.6 94.3
94.2 93.7 32.1 MCH 31.2 31.1 32.2 31.7 32.2 32.5 MCHC 327 325 341
336 344 353 RDW 13.93 12.1 12.7 12.9 12.9 13.2 METHgB 0.9 0.3 0.3
0.3 0.0 0.9
TABLE-US-00013 TABLE 12 Red Blood Cell Values as a Function of
Radiation Dose Received Total Dose (in kGy) Parameter 0 0.625 0.125
0.250 0.375 0.555 0.750 HGB 1.8 1.7 1.8 1.7 2.0 2.0 2.0 % O 96.6
96.5 96.2 96.3 96.4 96.5 96.0 % CO 1.0 1.2 1.6 1.3 1.7 1.5 1.5 %
NET 0.5 0.5 -0.5 0.4 -0.2 0.4 0.8 % Reduced 1.9 1.9 2.7 2.4 3.2 1.7
1.7 p60 (mm Hg) 34 nd nd nd nd nd 24 Hill 2.1 nd nd nd nd nd 1.8
Coefficient nd = not done The uncertainty with the methaemoglobin
levels is .+-.2%; with the p50 it is .+-.4% (95% confidence).
[0102] Having now fully described this invention, it will be
understood to those of ordinary skill in the art that the methods
of the present invention can be carried out with a wide and
equivalent range of conditions, formulations, and other parameters
without departing from the scope of the invention or any
embodiments thereof. All patents and publications cited herein are
hereby fully incorporated by reference in their entirety.
* * * * *