Joseph E. Losee

The osteogenic potential of adipose-derived stem cells for the repair of rabbit calvarial defects

Introduction: Bone replacement is often necessary during reconstruction of craniofacial anomalies or trauma. Adipose-derived stem cells (ASCs) possess osteogenic potential and are a promising cell source for bone tissue engineering. The present study was designed to assess the osteogenic potential and utility of using ASCs to regenerate bone in a rabbit calvarial defect model. Methods: Rabbit ASCs were seeded on gelatin foam (GF) scaffolds and induced in osteogenic medium containing bone morphogenetic protein (BMP)-2. Thirty-four 8-mm calvarial defects were randomly treated with autograft, no treatment, GF scaffold, GF + ASCs, or GF + osteoinduced ASCs. After 6 weeks, calvaria were harvested and underwent histologic and radiologic analyses to compare healing between the treatment groups. Results: Defects treated with autograft underwent complete healing. Radiologically, there were no significant (P > 0.05) differences in healing among empty defects, and those treated with GF alone or GF plus osteoinduced ASCs. Osteoinduced ASCs exhibited significantly (P < 0.05) greater healing than noninduced ASCs. Conclusion: Preimplantation osteoinduction of ASCs enhances their osteogenic capacity. Lack of a significant osteogenic effect of ASCs on calvarial healing at 6 weeks may be secondary to use of noncritical-sized defects. Larger defects would likely demonstrate the osteogenic potential of ASCs more definitively.

Upper-extremity transplantation using a cell-based protocol to minimize immunosuppression.

Objective: To minimize maintenance immunosuppression in upper-extremity transplantation to favor the risk-benefit balance of this procedure. Background: Despite favorable outcomes, broad clinical application of reconstructive transplantation is limited by the risks and side effects of multidrug immunosuppression. We present our experience with upper-extremity transplantation under a novel, donor bone marrow (BM) cell-based treatment protocol (“Pittsburgh protocol”). Methods: Between March 2009 and September 2010, 5 patients received a bilateral hand (n = 2), a bilateral hand/forearm (n = 1), or a unilateral (n = 2) hand transplant. Patients were treated with alemtuzumab and methylprednisolone for induction, followed by tacrolimus monotherapy. On day 14, patients received an infusion of donor BM cells isolated from 9 vertebral bodies. Comprehensive follow-up included functional evaluation, imaging, and immunomonitoring. Results: All patients are maintained on tacrolimus monotherapy with trough levels ranging between 4 and 12 ng/mL. Skin rejections were infrequent and reversible. Patients demonstrated sustained improvements in motor function and sensory return correlating with time after transplantation and level of amputation. Side effects included transient increase in serum creatinine, hyperglycemia managed with oral hypoglycemics, minor wound infection, and hyperuricemia but no infections. Immunomonitoring revealed transient moderate levels of donor-specific antibodies, adequate immunocompetence, and no peripheral blood chimerism. Imaging demonstrated patent vessels with only mild luminal narrowing/occlusion in 1 case. Protocol skin biopsies showed absent or minimal perivascular cellular infiltrates. Conclusions: Our data suggest that this BM cell-based treatment protocol is safe, is well tolerated, and allows upper-extremity transplantation using low-dose tacrolimus monotherapy.

Testing the critical size in calvarial bone defects: revisiting the concept of a critical-size defect.

Background: There is a clinical need for bone replacement strategies because of the shortfalls endemic to autologous bone grafting, especially in the pediatric patient population. For the past 25 years, the animal model that has been used to test bone replacement strategies has been the calvarial critical-size defect, based on the initial size of the bone defect. This study was undertaken to test the concept of the critical size in several different models. A review of the theoretical and scientific bases for the critical-size defect was also undertaken. Methods: Two different rodent species (including 28 adult mice and six adult rats) were used to assess bone healing by means of two-dimensional radiographic analysis after creating small bone defects using different surgical techniques. Results: Defects in mice that were smaller than critical-size defects (1.8-mm diameter) were shown to heal a maximum of 50 percent 1 year postoperatively. Small defects (2.3-mm diameter) in the rat skull showed approximately 35 percent healing after 6 weeks. Neither the choice of rodent species nor the maintenance of the dura mater significantly affected calvarial bone healing. Conclusions: These results suggest that calvarial bone healing is not well described and much more data need to be collected. Also, after a review of the existing literature and a critique of the clinical applicability of the model, it is suggested that the use of the term “critical-size defect” be discontinued.

The world's experience with facial transplantation: What have we learned thus far?

The objective of this review article is to summarize the published details and media citations for all seven face transplants performed to date to point out deficiencies in those reports so as to provide the basis for examining where the field of face transplantation stands, and to act as a stimulus to enhance the quality of future reports and functional outcomes. Overall long-term function of facial alloflaps has been reported satisfactorily in all seven cases. Sensory recovery ranges between 3 and 6 months, and acceptable motor recovery ranges between 9 and 12 months. The risks and benefits of facial composite tissue allotransplantation, which involves mandatory lifelong immunosuppression analogous to kidney transplants, should be deliberated by each institution’s multidisciplinary face transplant team. Face transplantation has been shown thus far to be a viable option in some patients suffering severe facial deficits which are not amenable to modern-day reconstructive technique.

Bone morphogenetic protein 2 therapy for craniofacial surgery.

Between 2 and 10 years of age, the developing craniofacial skeleton poses a significant reconstructive challenge. Local autogenous bone is largely unavailable, distant bone grafts are fraught with significant morbidity and limited yield, and alloplastic materials are incompatible with the growing calvarium and facial skeleton. Bone morphogenetic protein (BMP) 2, a member of a class of proteins first noticed in the 1960s to promote bone deposition in soft tissues, offers a potential solution to the bone shortage historically faced by the pediatric craniofacial surgeon. A review of English language literature was conducted from the 1960s to the present. Attention was focused on BMP-2s osteoinductive mechanism, basic science and translational laboratory findings, and multidisciplinary clinical experiences. Bone morphogenetic protein 2 has been embraced by spine surgeons, is gaining in popularity for long-bone repair, and is making its way into the plastic surgery literature. Bone morphogenetic protein 2 may provide a basis for an off-the-shelf tissue-engineered bone construct that is compatible with the growing craniofacial skeleton while free from the morbidities of distant graft harvest. Questions remain, however, regarding the safety and efficacy of this compound in the context of pediatric craniofacial surgery. In an effort to facilitate the clinicians risk-benefit analysis of this emerging technology, we present a primer on the basic science of BMP-2, a discussion of possible morbidities associated with its use, a review of laboratory and clinical trials with this substance to date, and an analysis of strategies to maximize its efficacy in craniofacial surgery.

The Pittsburgh Fistula Classification System: A Standardized Scheme for the Description of Palatal Fistulas

Objective: Vague terminology is a problem in cleft palate research. No classification scheme for palatal fistulas has been proposed to date. Although a well-healed velum is a significant outcome of palatoplasty, it is nearly impossible to compare fistula-related palatoplasty results in the literature or in medical records without a standardized vocabulary. We endeavor to devise a palatal fistula classification system that may have clinical and research applicability. Design: PubMed was searched for definitions and classifications of palatal fistula as well as incidence and recurrence rates of this outcome. Next, a 25-year retrospective review of our Cleft Centers records was performed, and fistulas were identified (n = 641 charts reviewed). The fistula descriptions yielded by this chart review were evaluated in the context of anatomical descriptions in the literature, and a clinician-friendly classification scheme was designed. Results: A literature review failed to reveal a standardized fistula classification system. An anatomically based numerical fistula classification system was devised: type I, bifid uvula; type II, soft palate; type III, junction of the soft and hard palate; type IV, hard palate; type V, junction of the primary and secondary palates (for Veau IV clefts); type VI, lingual alveolar; and type VII, labial alveolar. Conclusions: We propose a standardized numerical classification system for palatal fistulas. Its clinical adoption may prospectively clarify ambiguities in the literature and facilitate future cleft palate research and clinical practice.

Repair of oronasal fistulae with acellular dermal matrices.

Background: The authors examined the efficacy of a novel technique for oronasal fistula repair using acellular dermal matrix grafts. In part I, an animal model was used to demonstrate proof-of-concept; in part II, the method was applied to oronasal fistula repair in the clinical setting. Methods: In part I, oronasal fistulas were created in Yorkshire piglets (n = 6) and allowed to mature for 2 weeks. In three animals, acellular dermal grafts were interposed between the oral and nasal mucosa traversing the palatal fistulas. Mucosal edges were not closed. Three weeks postoperatively, the palates were examined histologically. The fistulas of control piglets (n = 3) remained unrepaired and were examined 5 weeks after their creation. In part II, acellular dermal grafts were interposed between the oral and nasal mucosa in nine consecutive patients undergoing oronasal fistula repair. Complete closure of the oral and nasal mucosa was achieved in two patients. In the remainder, nasal closure was affected by interposition of the dermal matrices beneath a complete oral mucosal closure. Results: All animals that underwent fistula repair demonstrated successful healing with revascularization, complete reepithelialization, and cellular infiltration into the grafts. All control fistulas remained patent. Successful fistula closure was observed in all patients. In two patients, early oral mucosal dehiscence and exposure of the dermal graft was followed by complete healing. Conclusions: This study demonstrates successful closure of palatal fistulas in an animal model and in cleft palate patients using interposition grafts of acellular dermis. This novel method offers promise as a simple and effective technique for tension-free closure of oronasal fistulas.

Congenital nasal anomalies: a classification scheme.

The purpose of this work was to develop a simple yet comprehensive classification scheme dedicated to congenital nasal anomalies. To date, no such classification system has been proposed and widely used. A 22-year retrospective review was performed. Two hundred sixty-one patients with congenital nasal anomalies were identified. From this extensive database, a systematic morphogenic classification system was devised. Congenital nasal deformities were classified into four categories. Type I, hypoplasia and atrophy, represents paucity, atrophy, or underdevelopments of skin, subcutaneous tissue, muscle, cartilage, and/or bone. Type II, hyperplasia and duplications, representing anomalies of excess tissue, ranging from duplications of parts to complete multiples, are categorized here. In the type III category, clefts, the comprehensive and widely utilized Tessier classification of craniofacial clefts is applied. Type IV deformities consist of neoplasms and vascular anomalies. Both benign and malignant neoplasms are found in this category.

Nonsynostotic occipital plagiocephaly: factors impacting onset, treatment, and outcomes.

Background: Nonsynostotic occipital plagiocephaly remains a diagnosis of concern in infancy. This study evaluates factors affecting the onset, treatment, and outcomes of nonsynostotic occipital plagiocephaly. Methods: A retrospective chart review and telephone survey were performed. A posterior occipital deformation severity score was used. Factors such as demographics, behavioral and helmet therapy, feeding patterns, torticollis, multiple gestation pregnancies, prematurity, and congenital nonsynostotic occipital plagiocephaly were evaluated. Results: One hundred five infants were identified. Of these, 95 percent were Caucasian, 93 percent were from two-parent households, and 70 percent were from households earning more than

A Successful Algorithm for Limiting Postoperative Fistulae following Palatal Procedures in the Patient with Orofacial Clefting

50,000. Repositioning was attempted in 95 percent, and 45 percent progressed to helmet therapy. When comparing change in posterior occipital deformation severity score with helmet therapy to repositioning, a difference was found (p < 0.05). Forty-nine percent of patients were breast-fed, and when compared with the general population, a difference was found (p < 0.05). Twenty percent of infants had torticollis, and when compared with population norms, a difference was found (p < 0.05). Twelve percent of patients were twins, and when compared with population norms, more twinning occurred (p < 0.05). Congenital nonsynostotic occipital plagiocephaly was found in 10 percent of patients and did not result in an increased risk of progression to helmet therapy. Conclusions: This study demonstrates trends that may predict additional risks for developing nonsynostotic occipital plagiocephaly, including torticollis, plural births, and increased socioeconomic affluence. In addition, the nonsynostotic occipital plagiocephaly cohort was breast-fed less than the general population, demonstrating that breast-feeding may be preventative, as breast-fed infants are repositioned more frequently and sleep for shorter periods. As in other studies, cranial molding helmet therapy was more effective in correcting nonsynostotic occipital plagiocephaly than repositioning alone.