Researchers One Step Closer Towards Xenotransplantation Of Pig Cells

Researchers One Step Closer Towards Xenotransplantation Of Pig Cells

According to a study conducted at Bellvitage Biomedical Institute, natural killer cells are the culprit behind porcine chondrocytes rejection. The study was published in The Journal Of Immunology and pointed out that natural killer cells activate the innate immune system, thus having a major role in xenotransplantation (organs or cells that are transplanted from another species) rejection mechanism.

Natural killer cells represent the first line of defence of the immune system, having a very important role in the not-acquired immune response, along with macrophages and neutrophils. NK cells are part of the innate response of the response of immune system. The main roles of natural killer cells are to identify and to destroy by toxic action specific aggressive factors like cancer cells, infectious germs or cells that are foreign to the body.

Microscopic Image of Natural Killer Cells

Normally, the human body has a small number of natural killer cells, but they play a major role in transplantation because acquired immunity (also regulating by NK cells) is the main factor that favorizes organ rejection.

With this study, scientists wanted to create porcine cartilage cells for human transplantation that cold repare injured cartilage without initiating an immune response that is responsible for rejection. To achieve this goal, researchers studied the action of natural killer cells in the presence of porcine chondrocytes. They observed that after transplantation, levels of antibodies and cytokines that have the property to activate natural killer cells are increased. Activated natural killer cells will destroy non-self cells by direct cytotoxic action.

“In this work we have characterized several molecules involved in the processes of adhesion and cytotoxicity of natural killer cells,” explained scientists. They believe that this study is the first step in investigating the reject action mediated by natural killer cells because “on one hand we have to fight the deposition of antibodies that is a critical factor in increasing the toxicity and on the other we must work to reduce cell adhesion by modifying any of the molecules we have involved.”

In conclusion, in order to achieve a cartilage xenotransplantation without rejection response, researchers must to modify the genetic conformation of porcine cartilage cells, so that the immune system and especially natural killer cells don not recognize this type of cells as non-self, thus avoiding rejection.

Transplantation of cartilage tissue does not represent a technique that is often encountered in medical practice, but was realized successfully in cartilage traumatic injuries. An autologous transplant represents harvesting cells from the same person and transplanting them back. Allogenic transplantation is defined as transplantating cells or tissues harvested from another person. Either way the major setback is represented by the limited amount of cells available. If patients could benefit from cartilage xenotransplantation, it would drastically increase the amount and quality of cells.

In the not so distant future, researchers hope to be able to help patients with osteoarthritis or even rheumatoid arthritis by xenotransplantation of pig condrocytes.