Induction of immunological tolerance

Abstract

A method of creating tolerance to transplanted cells, tissue, or organs without the need for continuous immunosuppression. A tolerizing dose of a cell or tissue within a membrane structure is implanted into a patient. Once the patient becomes tolerant to the cell or tissue, a tissue or organ is implanted which will no longer be recognized as foreign matter. The method makes animal organs, practical for human use, prevents autoimmune destruction as well as immune rejection. It has applications in treatment and prevention of many mammalian diseases.

Description

RELATED APPLICATIONS[0001]This application is a continuation of application Ser. No. 10 / 660,924, filed Sep. 12, 2003 (to be granted as U.S. Pat. No. 7,361,333 on Apr. 22, 2008), which is a continuation of application Ser. No. 09 / 226,742 filed Jan. 7, 1999, which is a continuation of application Ser. No. 09 / 049,757 filed Mar. 27, 1998 now abandoned, which is a continuation of application Ser. No. 08 / 736,413 filed on Oct. 24, 1996 now abandoned, which claims priority under 35 U.S.C. 119(e) of Provisional Application No. 60 / 005,877 filed Oct. 26, 1995.FIELD OF THE INVENTION[0002]The present invention relates to the induction of immunological tolerance to foreign cells, tissues and; organs. More specifically, the invention relates to implantation of a tolerizing dose of cells or tissues encapsulated in a membrane in a (mammal to establish immunological tolerance thereto.BACKGROUND OF THE INVENTION[0003]For some human diseases, including heart and liver failure, organ transplantation is ...

AI Technical Summary

Benefits of technology

[0023]The problems discussed in the foregoing Background of the Invention have previously not been solved for either micro or microencapsulation of cells in humans. The present invention overcomes these problems associated with transplantation. Thus, one goal of the invention is to eliminate the critical problems of transplantation in cases where whole organ transplantation is the only alternative to certain death. These are cases of heart or liver failure. The major advantage of the invention process for this application is that it eliminates the shortage of organs for the patients by making animal organs acceptable in humans. While there are only about 4,800 human organ donors in the U.S. each year, the supply of animal organs for transplant is not limited. The reason that animal organs are not presently used is that they are acutely rejected when transplanted into humans even with immunosuppression. Second, continuous immunosuppression is not required in the process of the invention, thus eliminating the risk of exposing the patient to other serious diseases while the immune system is suppressed. Third, the cost of organ transplantation is drastically reduced because of the unlimited supply of organs and because the continuous use of immunosuppressive drugs is not required.

[0024]A second goal of the invention is to make organ transplantation a safe, effective, practical therapy for those cases of disease where it is known now to be therapeutic but the risks associated with it prevent its widespread therapeutic use. Examples of these disease cases are kidney failure, pancreas failure and cystic fibrosis (lung failure). In these cases the advantages of the process of the invention eliminate the major obstacles. First, by making animal organs tolerated in humans the shortage of organs for these transplant needs is solved. Second, by eliminating the need for continuous immunosuppression, these patients are not exposed to other serious disease threats without a fully functioning immune system. Third, because of plentiful organs and no continuous immunosuppression, the cost of this transplant procedure would be greatly reduced.

[0025]A third goal of the invention is to make cell or tissue transplants, as opposed to whole organ transplants, a practical therapy in cases where cells or tissue alone can cure a disease state by providing a lacking or deficient protein, enzyme or peptide. Examples of these cases are insulin-secreting islet cells for Type I diabetes, Factor VIII-secreting hepatic cells for hemophilia, dopamine-secreting adrenal chromaffin cells for Parkinson's disease and collagen for arthritis. A significant advantage of the process of the invention for these cases is that animal tissue or genetically engineered tissue expressing an absent or deficient protein of interest can be used if human tissue is scarce. In addition, cell types other than the normal protein-secreting cells can be engineered to secrete the protein of interest. For example, myoblasts can be engineered by standard methods to secrete insulin. The use of such cells is also within the scope of the present invention. Continuous immunosuppression is not needed to protect the transplanted tissue and the costs would be reduced. Thus, even if pre-inoculation into the thymus with immunosuppression or irradiation of bone marrow with immunosuppression or monoclonal antibodies could be identified and produced for many disease states or encapsulation of fully therapeutic doses of tissue in some membrane device can overcome many

Problems solved by technology

Thus, because of timing and tissue matching problems, many patients die each year for lack of an available organ.

For those lucky enough to receive an organ, the results are still less than ideal.

The transplant procedure constitutes major surgery which is associated with attendant risks and is exceedingly expensive.

As a consequence, the patient's entire immune system is suppressed for the rest of his life, significantly lowering his defenses against other serious disease threats such as infections, viruses or cancers.

For still other diseases, transplantation is known to be effective, although its attendant problems preclude its practical therapeutic use.

Tissue transplantation requires full immunosuppression and carries the same risks and problems as already discussed for whole organ immunosuppression.

First, this has only been shown to work in rodents to date.

No large animal or human test has been successful.

Second, the human adult thymus is shrunken and may not be practical to treat with an adequate pre-dose.

Third, the immunosuppression step, while temporary, does subject the patient to risks for that period of time.

Fourth, it is not known whether a fully therapeutic dose will be tolerated, (i.e. not rejected) in humans.

Fifth, this procedure may not protect against autoimmune destruction even if it does prevent rejection.

First, this has not been shown to work for tissue transplants in humans.

Second, irradiation of immune cells, either partial or whole body, carries serious risks.

Third, it is not known if the immune system will adequately protect from other threats.

Fourth, it is not known if the method will protect from both rejection and autoimmune destruction in those disease states.

These tests have only been performed in rodents so it is not known if they would succeed in humans.

Also, it is not known if the proper monoclonal antibody could be identified and created for each different disease state.

There are several unresolved problems associated with this method.

First, none of these devices has been shown to protect a therapeutic transplant in humans.

In addition, it is not yet known where transplantation can actually prevent a disease from occurring other than the obvious case of whole organ failures.

Moreover, for many disease states, it is not known who will be afflicted.

Thus, a major role for preventive transplantation has not been investigated.

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