Transgenic expression of human cytoxic T-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) by porcine skin for xenogeneic skin grafting.

Porcine skin is frequently used as a substitute of human skin to cover large wounds in clinic practice of wound care. In our previous work, we found that transgenic expression of human cytoxicT-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) in murine skin graft remarkably prolonged its survival in xenogeneic wounds without extensive immunosuppression in recipients, suggesting that transgenic hCTLA4Ig expression in skin graft may be an effective and safe method to prolong xenogeneic skin graft survival. In this work, using a transgene construct containing hCTLA4Ig coding sequence under the drive of human Keratine 14 (k14) promoter, hCTLA4Ig transgenic pigs were generated by somatic nuclear transfer. The derived transgenic pigs were healthy and exhibited no signs of susceptibility to infection. The hCTLA4Ig transgene was stably transmitted through germline over generations, and thereby a transgenic pig colony was established. In the derived transgenic pigs, hCTLA4Ig expression in skin was shown to be genetically stable over generations, and detected in heart, kidney and corneal as well as in skin. Transgenic hCTLA4Ig protein in pigs exhibited expected biological activity as it suppressed human lymphocyte proliferation in human mixed lymphocyte culture to extents comparable to those of commercially purchased purified hCTLA4Ig protein. In skin grafting from pigs to rats, transgenic porcine skin grafts exhibited remarkably prolonged survival compared to the wild-type skin grafts derived from the same pig strain (13.33 ± 3.64 vs. 6.25 ± 2.49 days, P < 0.01), further indicating that the transgenic hCTLA4Ig protein was biologically active and capable of extending porcine skin graft survival in xenogeneic wounds. The transgenic pigs generated in this work can be used as a reproducible resource to provide porcine skin grafts with extended survival for wound coverage, and also as donors to investigate the impacts of hCTLA4Ig on xenotransplantation of other organs (heart, kidney and corneal) due to the ectopic transgenic hCTLA4Ig expression.

[Development of therapeutic antibodies for gastric and colorectal cancers].

With the elucidation of structures and functions, antibodies are widely applied in the diagnosis and treatment of diseases. Today, therapeutic antibodies have played ever increasing roles in the treatment of cancers. In fact, there are over 20 monoclonal antibodies which have been approved by the U.S.Food and Drug Administration (FDA) for the therapeutic use in cancers. For the gastric and colorectal cancers, there are at least 9 antibodies have been approved for cancer therapy or for clinical trials. These antibody drugs target to tumor associate antigens and can destroy the cancer cells through several mechanisms such as antibody-dependent cell cytotoxicity, complement-dependent cytotoxicity, blockage of blood nutrition and crucial signaling pathways. With the progress in gene engineering technology, the diverse structures of antibodies can be created. In addition, the antibody-conjugates with radioisotopes, toxins and cytotoxins, are also designed for targeted therapy of gastric and colorectal cancers. In this article, we review the trends in the clinical development and application of antibody drugs for future research and development of the rapidly expanding therapeutic modality in gastric and colorectal cancers.