The Council of Agriculture has supported the Agricultural Technology Research Institute (ATRI) to develop genetically modified pigs for various purposes. The ATRI is currently involving in a joint project with Taipei Medical University to establish a manufacturing process of porcine cornea decellularization. Thus far the project has already established 7 types of processes to develop porcine cornea scaffold with a high biocompatibility and potentially beneficial for 3 million patients needing corneal transplant around the world.
Application of genetic modification technology for upgrading biocompatible medical material
The COA stated that NGNA type sialic acid synthase gene in both pigs and human is responsible for organ transplant rejection. Once the synthase gene’s action could be depressed, graft rejection should be avoided and becoming a highly biocompatible medical material for organ transplant. ATRI inherited the experiences accumulated by the Animal Technology Institute Taiwan (ATIT) in producing transgenic pigs and successfully applied the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology to trigger synthase gene mutation in pigs and thus eliminating it in the animal. Currently 4 piglets without NGNA type sialic acid antigen were born and could serve as a source of medical material for NGNA antigen-free highly biocompatible cornea scaffold in the future. The team is continuously working with Taipei Medical University to conduct functional evaluation.
Among most of the organ and tissue transplantation, the cornea's immunologic rejection was relatively low. There have even been reports from abroad about the preclinical tests of ordinary pig cornea transplanted into non-human primates and could last or maintain translucency for more than 900 days. It has suggested that this decellularized tissue scaffold could be used for partial cornea transplantation and treatment since it possesses advantages such as better translucency, physiological corneal curvature, biocompatibility, and mechanical stability. However, these scaffold materials still contain carbohydrates such as galactose and sialic acid which would cause immunologic rejection. Therefore, the ATRI is actively conducting relevant gene knockout research to overcome such an obstacle.
Breeding genetically modified pigs is helpful to organ transplant
The COA pointed out that in addition to the decellularized cornea, the accumulated results of ATRI's work on breeding genetically modified pigs could also be applied to various medical materials such as heart valve, dental film, and bone meal among others. It is expected that this research would be successfully transferred and commercialized to become products. In the future, highly biocompatible fresh pig tissues (such as corneas and islet cells) or physical organs (such as kidney and heart) could be used as xenograft. The ATRI is devoting its efforts in working with medical centers or medical schools to overcome the problem of rejection in xenotransplantation by means of the genetically modified anti-rejection pigs with a hope to provide xenograft of patients waiting for organ transplant.