Composite tissue allotransplantation for the reconstruction of congenital craniofacial defects

The current outcomes and future challenges in pediatric vascularized composite allotransplantation

PURPOSE OF REVIEW

We review the outcomes and future challenges associated with pediatric vascularized composite allotransplantation, including follow-up data from our bilateral pediatric hand-forearm transplantation.

RECENT FINDINGS

In 2015, the first heterologous pediatric upper extremity hand-forearm transplant was performed at the Children's Hospital of Philadelphia, and in 2019, the first pediatric neck reconstructive transplantation was performed in Poland. The 5-year follow-up of the pediatric upper extremity recipient demonstrates similar growth rates bilaterally, an increase in bone age parallel to chronologic age, and perhaps similar overall growth to nontransplant norms. The pediatric upper extremity recipient continues to make gains in functional independence. He excels academically and participates in various extracurricular activities. Future challenges unique to the pediatric population include ethical issues of informed consent, psychosocial implications, limited donor pool, posttransplant compliance issues, and greater life expectancy and therefore time to inherit the many complications of immunosuppression.

SUMMARY

Currently, we recommend pediatric vascularized composite allotransplantation (VCA) for bilateral upper extremity amputees, preferably on immunosuppression already, and those patients who would have the most potential gain not available through standard reconstructive techniques while being able to comply with postoperative immunosuppression protocols, surveillance, rehabilitation, and follow-up.

Oral cyclosporine A in neonatal swines for transplantation studies

The purpose of this study is to define the optimal dose of oral cyclosporine A (CsA) microemulsion in newborn swine for transplantation studies and to describe its pharmacokinetics and acute renal effects in short-term administration. Thirteen neonatal pigs were randomized into four groups: one control and three groups with CsA administration at 4, 8 and 12 mg/kg/d for 15 days (D). Blood samples were collected on D 0, 2, 4, 9 and 14 to determine the changes of the CsA trough concentrations, the creatinine (Cr) and blood urea nitrogen (BUN) serum concentrations. On D 14, blood samples were collected every hour from 1 h to 10 h after CsA administration to determine the area under the curve (AUC). On D 15, kidneys were removed for histological analysis. We observed a stabilization of CsA trough concentrations from D 4 to D 14. On D 14, in the three treated groups, CsA trough concentrations were 687 ± 7, 1200 ± 77 and 2211 ± 1030 ng/ml, respectively; AUC (0-10 h) were 6721 ± 51 ng·h/ml in group 4 mg/kg/d, 13431 ± 988 ng·h/ml in group 8 mg/kg/d and 28264 ± 9430 ng·h/ml in group 12 mg/kg/d. Cr concentrations were not significantly different among the four groups; but compared to control group, BUN concentrations of the three treated groups increased significantly. CsA was well tolerated; neither acute, severe adverse event nor renal histological abnormality was observed. In conclusion, a 15-d course of oral CsA treatment ranged from 4 to 12 mg/kg/d is safe for newborn pigs, which need much lower CsA dose than adult pigs to reach comparable trough level and AUC. As immunosuppressive therapy in newborn pigs, we recommend a CsA dose of 4 mg/kg/d to achieve a trough blood concentration between 400 and 800 ng/ml.

Facial appearance transfer and persistence after three-dimensional virtual face transplantation

BACKGROUND

Facial appearance transfer from donor to recipient in face transplantation is a concern. Previous studies of facial appearance transfer and facial appearance persistence (preservation of the recipient's facial likeness) in face transplants simulated using two-dimensional photographic manipulations found low facial appearance transfer (2.6 percent) and high facial appearance persistence (66 percent). Three-dimensional computer simulation of complex facial transplant patterns may improve the accuracy of facial appearance transfer and facial appearance persistence estimations.

METHODS

Three-dimensional virtual models of human faces were generated from deidentified computed tomographic angiographs and used as "donors" or "recipients" for virtual face transplantation. Surgical planning software was used to perform 73 virtual face transplantations by creating specific facial defects (mandibular, midface, or large) in the recipient models and restoring them with allografts extracted from the donor models. Twenty independent reviewers evaluated the resemblance of each resulting posttransplant model to the donor (facial appearance transfer) and recipient (facial appearance persistence). The results were analyzed using tests for equal results with one-sample and pairwise Rao-Scott Pearson chi-square testing, correcting for clustering and multiple testing.

RESULTS

Overall rates of facial appearance persistence and facial appearance transfer were high (69.2 percent) and low (32.4 percent), respectively. The mandibular pattern had the highest rates of facial appearance persistence and lowest rates of facial appearance transfer. Facial appearance persistence and transfer were similar across sexes.

CONCLUSIONS

Facial appearance persistence is high and facial appearance transfer is low after virtual face transplantation. Appearance transfer and persistence after virtual face transplantation are more dependent on the anatomy than on the size of transplanted facial aesthetic units. This information may reassure recipients of partial face transplants and donor families.

Face allotransplantation and burns: a review

Burns may represent one of the main indications for face allotransplantation. Severely disfigured faces featuring a devastating appearance and great functional impairments are not only seen as burn sequelae but also occur as a result of other traumatic injuries, oncological surgical resections, benign tumors (eg, neurofibromatosis), and major congenital malformations. To date, 20 human face composite tissue allotransplants have been performed with success. Despite the initial scepticism about its applicability, due mainly to ethical and technical reasons, the previous worldwide cases and their associated positive outcomes, including acceptable immunosuppressive regimens, excellent aesthetic and functional results, and good psychological acceptance by the recipient, enable the conclusion that face composite tissue allotransplantation has become another therapeutic strategy in the reconstructive surgical armamentarium, which bears special consideration when dealing with severely disfigured burned patients. The aim of this review is to describe the basics of face composite tissue allotransplantation and give an overview of some of the cases performed until now, with special attention paid to debating the pros and cons of its applicability in burn patients.