Replantation of the radial side of the hand in the rhesus monkey: anatomical and functional aspects. A preliminary study to composite tissue allografting

A concise review of common animal models for the study of limb regeneration

Correct selection of an appropriate animal mode to closely mimic human extremity diseases or to exhibit desirable phenotypes of limb regeneration is the first critical step for all scientists in biomedical and regenerative researches. The commonly-used animals in limb regeneration and repairing studies, such as axolotl, mice, and rats, are discussed in the review and other models including cockroaches, dogs, and horses are also mentioned. The review weighs the general advantages, disadvantages, and precedent uses of each model in the context of limb and peripheral injury and subsequent regeneration. We hope that this review can provide the reader an overview of each model, from which to select one for their specific purpose.

Primate models in organ transplantation

Large animal models have long served as the proving grounds for advances in transplantation, bridging the gap between inbred mouse experimentation and human clinical trials. Although a variety of species have been and continue to be used, the emergence of highly targeted biologic- and antibody-based therapies has required models to have a high degree of homology with humans. Thus, the nonhuman primate has become the model of choice in many settings. This article will provide an overview of nonhuman primate models of transplantation. Issues of primate genetics and care will be introduced, and a brief overview of technical aspects for various transplant models will be discussed. Finally, several prominent immunosuppressive and tolerance strategies used in primates will be reviewed.

Animal models for basic and translational research in reconstructive transplantation

Reconstructive transplantation represents a bona fide option for select patients with devastating tissue loss, which could better restore the appearance, anatomy, and function than any other conventional treatment currently available. Despite favorable outcomes, broad clinical application of reconstructive transplantation is limited by the potential side effects of chronic multidrug immunosuppression. Thus, any reconstructive measures to improve these non-life-threatening conditions must address a delicate balance of risks and benefits. Today, several exciting novel therapeutic strategies, such as the implementation of cellular therapies including bone marrow or stem cells that integrate the concepts of immune regulation with those of nerve regeneration, are on the horizon. The development of reliable and reproducible small and large animal models is essential for the study of the unique immunological and biological aspects of vascularized composite allografts and to translate such novel immunoregulatory and tolerance-inducing strategies and therapeutic concepts from the bench to bedside. This review provides an overview of the multitude of small and large animal models that have been particularly designed for basic and translational research related to reconstructive transplantation.

Research and Events Leading to Facial Transplantation

Facial transplantation has long captured the interest and imagination of scientists, the media, and the lay public. Facial transplantation could provide an excellent alternative to current treatments for facial disfigurement caused by burns, trauma, cancer extirpation, or congenital birth defects. This article discusses the major technical, immunologic, psychosocial and ethical hurdles that have been overcome to bring facial transplantation from an idea to a clinical reality by providing the reader with a chronologic overview of the research and events that have led this exciting new treatment into the clinical arena.

Comparative anatomy of the subsynovial connective tissue in the carpal tunnel of the rat, rabbit, dog, baboon, and human

The tenosynovium in the human carpal tunnel is connected to the flexor tendons and the median nerve by the subsynovial connective tissue (SSCT). The most common histological finding in carpal tunnel syndrome (CTS), a compression neuropathy of the median nerve, is noninflammatory fibrosis of the SSCT. The relationship, if any, between the fibrosis and nerve pathology is unknown, although some have speculated that a change in the SSCT volume or stiffness might be the source of the compression. Yet, while animal models have been used to study the physiology of nerve compression, so far none have been used to study the relationship of the SSCT pathology to the neurophysiological abnormalities. The purpose of this study was to identify animal models that might be appropriate to study the interaction of SSCT and nerve function in the development of CTS. The front paws of a rat, rabbit, dog, and baboon were dissected. The carpal tunnel anatomy and SSCT of these animals were also examined by light and scanning microscopy and compared to the relevant human anatomy and ultrastructure. The carpal tunnel anatomy and contents of the baboon and rabbit are similar to humans. The canine carpal tunnel lacks the superficial flexor tendons and the rat carpal tunnel is very small. The human, baboon, and rabbit specimens had very similar organization of the SSCT, and content of the carpal canal. We conclude that, while both the baboon and rabbit would be good animal models to study the relationship of the SSCT to CTS, the rabbit is likely to be more practical, in terms of cost and animal care concerns.

Swine composite tissue allotransplant model for preclinical hand transplant studies

Our laboratory previously developed and used an orthotopic radial forelimb osteomyocutaneous flap in the pig as a preclinical composite tissue allograft (CTA) model. To ensure that it mimicked the clinical situation as closely as possible we developed this model taking many immunologic and reconstructive considerations into account. While our original pig CTA model was ideal for studying the methods of preventing skin, muscle, bone, vessel and nerve rejection, and systemic toxicity, it did not include specialized tissues/structures of a joint and digit. Therefore, we were unable to evaluate rejection of these specialized tissues and their functional properties. Recognizing the importance of assessing joint rejection and function in hand transplantation research we developed a new swine forelimb CTA model that included the animal's medial digit. The present study describes the anatomy and the transplantation technique used in this new preclinical CTA model. We transplanted a radial osteomyocutaneous flap that included the medial digit between two size- (17-21 kg) and age- (6-8-week) matched farm pigs. We removed the digit from the recipient pig's forelimb in continuity with a section of the radial bone and replaced it with the same structure transplanted from a donor pig. After transplantation, a full-length cast was placed on the recipient pig's operated limb and changes in flap color, temperature and the presence of edema were monitored continuously for 6 h, and then regularly at predetermined intervals over 4 days. No weight bearing restrictions were placed on the animal's operated limb. After 4 days, the animal was euthanized. Direct visual monitoring of the allograft during 4 days revealed it was viable with no signs of graft failure due to technical complications associated with the transplant procedure. Upon waking from anesthesia, the animal stood and wandered freely about its cage with no apparent difficulty. Based on the animal's high level of activity at this time, we concluded that the procedure caused it minimal morbidity. At 4 days after the operation, early signs of rejection (skin erythema and edema) were observed. By incorporating a digit into our original CTA pig forelimb model we have made it a better model for performing preclinical hand transplant studies. The added advantage of being able to assess methods of preventing rejection in the specialized joint/digital tissues (articular cartilage, digital flexor and extensor systems, the nail complex) and assess long-term function of these structures is important. The fact that the procedure does not cause major morbidity to the animal makes it possible to conduct long-term graft survival and functional studies.