Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Blood proteins or globulins – e.g. – proteoglycans – platelet...
Patent
1997-08-01
1998-11-03
Tsang, Cecilia J.
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Blood proteins or globulins, e.g., proteoglycans, platelet...
530383, 530421, 530418, A61L 204, A61L 2500, C07K 1475, C07K 14755
Patent
active
058310274
DESCRIPTION:
BRIEF SUMMARY
This application is a U.S. national stage application of PCT/GB95/02902 filed on Dec. 8, 1995.
TECHNICAL FIELD
The present invention relates to the production of cryoprecipitatable blood plasma proteins, such as fibrinogen, which are capable of being severely heat treated in order to substantially inactivate major blood-borne viruses that may be present; whilst at the same time maintaining the desirable properties of the plasma protein, such as solubility in aqueous solution and functional (e.g. clotting) activity.
BACKGROUND
As is well known, blood plasma contains a series of coagulation factors which contribute to clot formation. Recently, a type of natural glue referred to as fibrin sealant has been prepared utilising certain of these blood coagulation factors. Thus, fibrinogen when combined with thrombin will form fibrin, an insoluble adhesive biological polymer. When Factor XIII is also present, cross-linking of the fibrin occurs which stabilises and strengthens the clot which is formed. The use of fibrinogen and thrombin concentrates in this way represents a major technical advance in surgery (references 1 to 4). Indeed, several fibrin sealant products are available commercially and have been used extensively in a number of European countries. By way of example, patent specifications GB2041942, GB2042556 and WO86/01814 describe various ways of producing fibrin sealant preparations. In practice, fibrin sealant has found a variety of surgical uses including the repair of vascular and anastomoses, repair of soft tissue injuries e.g. of the liver and spleen, and repair of lung lascerations.
The fibrin sealant is generally provided as two separate concentrates of fibrinogen and thrombin respectively, which are mixed shortly prior to use. Clotting of the fibrin sealant can take place relatively rapidly and specialised applicators for applying the fibrin sealant to a wound are disclosed in a number of patent specifications such as EP0037393, EP0315222, EP0156098 and U.S. Pat. No. 4,650,678.
In addition to its use as a component in fibrin sealant, suitable preparations of fibrinogen can also be infused to treat disorders such as hypo-, dys- and afibrinogenaemia.
However, despite the apparent effectiveness of such products, their use in the United Kingdom and the USA has up till now been limited partly because of availability but also because of fears of the transmission of blood-borne viruses by fibrinogen based preparations (reference 5). Typically, each human plasma donation is screened for the following virus markers; hepatitis B surface antigen, antibodies to human immuno deficiency virus (HIV) types 1 and 2, and hepatitis C virus, using validated test methods. Although such screening procedures have contributed greatly to the safety of blood products, there is a residual risk of virus contamination. Therefore a variety of methods for viral inactivation of blood products are known, including the use of detergents and heat treatment. However, these are of varying reliability. Terminal heat treatment of dry product has been widely proposed as a safe and effective method of virus inactivation and is referred to for example in patent specifications EP00944611, PCT/US90/01088, EP0345246, EP0159311 and EP0183674. In terminal heat treatment, the heating is carried out as a last step in the processing thereby eliminating the chances of recontamination.
However, terminal heat treatment has a number of potential disadvantages which detract from the utility of the procedure. Thus, in order to provide a sufficiently high level of virus inactivation, it may be desirable to heat at a temperature of at least 70.degree. C. for 50 to 100 hours. Under such severe heat treatment conditions, the plasma protein is liable to undergo undesirable degradations which may result in reduced biological activity. Furthermore, the solubility of the plasma protein on reconstitution prior to use may be significantly reduced.
A high-yield Factor VIII concentrate suitable for severe terminal heat treatment has been disclosed by one
REFERENCES:
patent: H1509 (1995-12-01), Eran et al.
patent: 4739039 (1988-04-01), Vasquez et al.
patent: 4816251 (1989-03-01), Seelich
patent: 5099002 (1992-03-01), Rubinstein et al.
patent: 5610147 (1997-03-01), Seelich et al.
Hardy John Charles
McIntosh Ronald Vance
Common Services Agency
Tsang Cecilia J.
Wang Cecilia
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