Tissue transplants in primates for upper extremity reconstruction: a preliminary report

Area of Science:

• Transplantation Surgery
• Neurosurgery
• Immunology

Background:

• Clinical advances in transplantation surgery raise the possibility of hand transplantation.
• Key questions remain regarding composite tissue survival and neural reinnervation under immunosuppression in primates.

Purpose of the Study:

• To investigate the survival of composite tissue transplants in a primate model.
• To determine if neural reinnervation occurs in transplanted hands under immunosuppression.

Main Methods:

• Performed four hand transplants and seven neurovascular free flap transplants in baboons.
• Administered immunosuppression using Cyclosporin A and steroids (methylprednisolone).
• Utilized electrophysiologic tests to assess neural reinnervation of skin, muscle, joints, and muscle spindles.

Main Results:

• Achieved long-term survival in nine out of eleven transplants.
• Demonstrated sensory axon reinnervation of transplanted skin with well-defined receptive fields.
• Confirmed motor unit recruitment in donor muscle upon stimulation of recipient nerves, indicating functional reinnervation.
• Observed afferent fibers serving donor joints and muscle spindles.

Conclusions:

• Composite tissue transplants, including hand transplants, can survive long-term in primates.
• Successful neural reinnervation of both sensory and motor pathways occurs in transplanted limbs under immunosuppression.
• These findings support the feasibility of clinical hand transplantation in humans.