To evaluate the effect of pig-monkey skin transplantation using GGTA1/β4GalNT2 double gene knockout inbred Wuzhishan miniature pig.

Donor pig split skins were taken from double gene knockout inbred Wuzhishan miniature pigs and wild type Wuzhishan inbred miniature pigs. The recipients were rhesus monkeys. According to different skin graft donors, they were divided into experimental group and control group, 4 in each group. Four full-thickness skin excision wounds were made on the back of each rhesus monkey, and double-knocked-gene pig skin and wild-type pig skin were transplanted respectively. The color and texture of the grafted skin were observed at different time points after the operation, the vitality of the skin was evaluated, and specimens were taken for pathological examination. Serum were collected at different time points to detect the contents of IL-2, IL-4, IL-12, IFN-γ and IFN-γ/IL-4.

The average survival time of double-knock-out pigskin was (13.9±3.1)days, which was longer than that of wild-type pigskin (11.0±2.0)d (t=-3.0901, P=0.0043). In the early postoperative period, both groups of skins survived well. On the 7th day after the operation, the double-knockout pig skin grafts were still ruddy, and some wild-type pig skins showed rejection manifestations such as big or small blisters, or cyanosis. On the 10th day after the operation, the texture of the double gene knockout skin grafts were softer than that of the wild type pig skin. The cyanosis of the wild type pig skin still exists. On the 12th day after the operation, some double gene knockout skin grafts were still intact and soft, however, intact and ruddy skin grafts could not be found in wild-type pigskin grafts. On the 14th day after the operation, 9 and 14 grafts of double-knock-out pigskin and wild-type pigskin were completely peeled off, respectively. The shedding rate of double-knock-out pigskin was lower than that of wild pig skin group (Pearson chi²=3.8647, P=0.049). Among the 7 double-knockout pig grafts still presented in the wound, two grafts were still ruddy, warm, and soft, and the two grafts turned to crust and lost viablity on the 21st day after surgery. Pathological observation showed that there was no significant difference in the early stage after the two types of skin transplantation. On the 7th day after the operation, the number of epidermal cells decreased and dermal collagen tissue were edema in the epidermis of two types of pig skin. Small vacuoles appeared in the epidermis of wild-type pig skin. A part of double-knocked pig skin and wild-type pig skin were closely connected to the wound bed to form an " engraft". On the 10th day after operation, the number of epidermal cells in the two types of pig skin continued to decrease compared with before, and vacuoles were seen in the epidermis. Among them, the vacuoles in the epidermis of the double-knock gene pigskin were similar to iof the wild-type pig skin increased significantly compared with the previous ones. Both grafts and the wound bed were still tightly connected. On the 14th day after the operation, the overall structure of some double-knocked pig skins remained basically intact, but the vacuoles in the epidermis were significantly enlarged, so that most of the epidermis and dermis were separated, and the dermis was still connected to the wound bed. After the wild-type pig skin fell off, the wound bed was exposed, the granulation tissue proliferated and a large number of inflammatory cells infiltrated. There was no regular change in the levels of serum IL-2, IL-4, IL-12, IFN-γ and IFN-γ/IL-4 between the two groups.

The immune rejection of GGTA1/β4GalNT2 double gene knockout inbred line Wuzhishan miniature pig skin is reduced and its survival time is prolonged. It has the prospect of clinical application to treat burn wounds.