Kia M. Washington

Composite tissue vasculopathy and degeneration following multiple episodes of acute rejection in reconstructive transplantation.

Transplant vasculopathy has not been systematically investigated in composite tissue allotransplantation (CTA). The impact of multiple acute rejections (ARs) on long‐term graft outcomes in reconstructive transplantation remains unknown. This study in a rat hind‐limb allotransplantation model systematically analyzes vasculopathy and tissue‐specific pathological changes secondary to multiple AR episodes. LEW rats were transplanted with BN rat hind limbs and treated as follows: Group 1 (Iso): isografts. Group 2 (CsA): Cyclosporine (CsA) qd; Group 3 (mult AR): CsA and dexamethasone only when AR was observed. No AR was observed in Groups 1 and 2. Multiple AR were observed in Group 3, and each episode was completely reversed (clinically) with pulsed CsA + dexamethasone treatment. Group 3 animals demonstrated significant vascular lesions along with skin and muscle atrophy, upregulation of profibrotic gene expression and fibrosis when compared to Groups 1 and 2. In addition, allograft bone was sclerotic, weak and prone to malunion and nonunion. Interestingly, vasculopathy was a late finding, whereas muscle atrophy with macrophage infiltration was seen early, after only a few AR episodes. Taken together, multiple AR episodes lead to vasculopathy and tissue‐specific pathology in CTA. This is the first evidence of ‘composite tissue vasculopathy and degeneration (CTVD)’ in CTA.

Daily topical tacrolimus therapy prevents skin rejection in a rodent hind limb allograft model.

Background: Skin is the most immunogenic component of a composite tissue allograft. Topical immunotherapy is an attractive therapeutic modality with which to provide local immunosuppression, with minimal systemic toxicity. The present study was performed to investigate the potential of topical tacrolimus to prolong survival of the skin component of a composite tissue allograft. Methods: Wistar Furth–to-Lewis rat orthotopic hind limb transplants were performed. Group I consisted of rats treated with topical tacrolimus; group II, antilymphocyte serum plus 21 days cyclosporine; and group III, antilymphocyte serum plus 21 days of cyclosporine plus topical tacrolimus. In group IV, tacrolimus levels in blood, skin, and muscle were measured in an autograft control group. Results: All animals in group I (n = 8) developed grade III clinical rejection by postoperative day 9. In group II (n = 9), the median onset of grade III rejection was postoperative day 40 (range, postoperative days 34 to 44). In group III (n = 6), two animals developed focal grade III rejection on postoperative days 35 and 56. The remaining four animals reached the 100-day endpoint without grade III rejection. In group IV, tacrolimus levels were low or undetectable in blood, whereas skin levels were 100-fold higher than underlying muscle. Conclusions: Topical tacrolimus therapy has the potential to prevent skin rejection in a composite tissue allograft. Preoperative depletion of T cells with antilymphocyte serum, along with a short course of systemic immunosuppression, prevents acute rejection, whereas topical tacrolimus inhibits immune cell function in the skin. Concentrations of tacrolimus are substantially higher in skin compared with underlying muscle and peripheral blood. Topical immunotherapy could reduce the morbidity associated with systemic immunosuppression in clinical composite tissue allografts.

Investigation of Antibody-Mediated Rejection in Composite Tissue Allotransplantation in a Rat Limb Transplant Model

BACKGROUND Despite the widely accepted implication of antidonor antibodies and complement in solid organ transplantation, their role in reconstructive allotransplantation is not clear. The aim of this study was to analyze the humoral immune response using a rat orthotopic limb transplantation model. METHODS We used the Brown Norway to Lewis rat orthotopic hind-limb transplant model: Group 1, isografts; group 2, allografts with daily continuous cyclosporine treatment to prevent acute rejection; and group 3, allografts undergoing multiple episodes of acute rejection. Samples were taken at 30, 60, and 90 days. Serum was analyzed by FACS for antidonor antibodies. Tissue deposition of antibodies and complement was investigated by immunofluorescence. RESULTS By day 90, animals in group 3 had undergone 19 (+/-3.2) acute rejection episodes. There was no difference in the occurrence of serum antidonor antibodies between the three groups at any time point. However, at 90 days, anti-third-party antibodies were significantly greater among group 3. There was no difference in antibody or complement deposition in muscles between the 3 groups. CONCLUSION Despite the increased antibody against a third party after multiple rejection episodes in this animal model, there was no clear evidence of an antibody-mediated alloresponse in limb transplantation.

A Model for Functional Recovery and Cortical Reintegration after Hemifacial Composite Tissue Allotransplantation

Background: The ability to achieve optimal functional recovery is important in both face and hand transplantation. The purpose of this study was to develop a functional rat hemifacial transplant model optimal for studying both functional outcome and cortical reintegration in composite tissue allotransplantation. Methods: Five syngeneic transplants with motor and sensory nerve appositions (group 1) and five syngeneic transplants without nerve appositions (group 2) were performed. Five allogeneic transplants were performed with motor and sensory nerve appositions (group 3). Lewis (RT1l) rats were used for syngeneic transplants and Brown-Norway (RT1n) donors and Lewis (RT1l) recipients were used for allogeneic transplants. Allografts received cyclosporine A monotherapy. Functional recovery was assessed by recordings of nerve conduction velocity and cortical neural activity evoked by facial nerve and sensory (tactile) stimuli, respectively. Results: All animals in groups 1 and 3 showed evidence of motor function return on nerve conduction testing, whereas animals in group 2, which did not have nerve appositions, did not show electrical activity on electromyographic analysis (p < 0.001). All animals in groups 1 and 3 showed evidence of reafferentation on recording from the somatosensory cortex after whisker stimulation. Animals in group 2 did not show a cortical response on stimulation of the whiskers (p < 0.001). Conclusion: The authors have established a hemiface transplant model in the rat that has several modalities for the comprehensive study of motor and sensory recovery and cortical reintegration after composite tissue allotransplantation.

Composite Tissue Allotransplantation for the Reconstruction of Congenital Craniofacial Defects

Facial disfigurement in children with congenital craniofacial defects can lead to decreased self-esteem and poor self-perception. Traditional methods of reconstruction can fail to achieve a normal appearance in patients with severe disfigurements. Composite tissue allotransplantation (CTA) in children could offer a unique reconstructive opportunity. A discussion of the usage of CTA for congenital craniofacial defects is thus warranted. Treatment of severe craniofacial clefts, Treacher-Collins syndrome, hemifacial microsomia, and some vascular anomalies can yield unsatisfactory results, even after multiple surgeries. CTA provides the advantage of intact vascularized bone that would not need to be reshaped to fit the defect, with the correct donor match. CTA also provides reconstruction with similar tissue type in regions of the central midface such as the nose, lips, and eyelids. With advances in transplant immunology to devise mechanisms to decrease immunosuppression and induce donor antigen-specific tolerance, CTA may be a future reality in the pediatric population.

Functional outcomes following multiple acute rejections in experimental vascularized composite allotransplantation

Background: Vascularized composite allotransplantation has become a clinical reality. Patients undergoing vascularized composite allotransplantation have modest functional return. Most patients have had multiple acute rejections. The effect of multiple acute rejections influencing functional outcomes is unknown. This study systematically analyzes the effects of multiple acute rejections on functional outcome. Methods: Rat functional orthotopic hind-limb transplants were performed from Brown-Norway to Lewis rats. Group 1 consisted of isografts. In group 2, daily cyclosporine was administered to prevent acute rejection. In group 3, recipients did not receive regular immunosuppression but received only pulsed cyclosporine and dexamethasone to rescue acute rejection. The study endpoint was 90 days. Muscle and sciatic nerve biopsy specimens were taken for histologic analyses. Hind-limb function was assessed using sciatic nerve axon density, nerve conduction velocity, and muscle force generated by the gastrocnemius muscle. Novel video kinematics was used to analyze gait. Results: By the endpoint, group 3 animals had 17 ± 5.1 acute rejections. Muscle biopsy showed significant atrophy and fibrosis in group 3 compared with groups 1 and 2. Withdrawal to pin prick was evident by days 31 ± 1.2, 30 ± 2.3, and 31 ± 3.7 in groups 1, 2, and 3, respectively. At the endpoint, there was no significant difference in the axon density or nerve conduction velocity among the three groups, but muscle force generated was significantly less in group 3. Gait was abnormal in group 3 animals compared with other groups. Conclusions: In this study, multiple acute rejections induced muscle atrophy and fibrosis and consequent decreased function. This emphasizes the importance of preventing acute rejection to achieve optimum function following vascularized composite allotransplantation.

Neck burn reconstruction with pre-expanded scapular free flaps

BACKGROUND The reconstruction of neck contracture deformities after severe burns is challenging. This is due to insufficient tissue to resurface the large defect after local flap transfer as well as the poor functional and cosmetic results after traditional methods such as skin grafting. We employed free transfer of pre-expanded scapular flaps to reconstruct postburn neck deformities. METHODS In the first stage, skin expansion was performed with tissue expanders ranging from 400 to 800 mL according to the neck defect size and expanders were filled to their end volumes. In the second stage, the contracture in the neck was released and the unstable scar was resected. The pre-expanded scapular flap was then harvested and transferred to the neck defect. Flap revisions were performed 3-12 months after flap transfer. RESULTS A total of 12 flaps (100%) were successful. The contour, colour, and texture of flaps matched well to the nearby skin. The range of motion of the neck was significantly improved. The donor defects were closed directly except for one case, which required skin grafting. CONCLUSIONS The free tissue transfer of pre-expanded scapular flap is a valuable tool in neck burn reconstruction. It can be used safely and effectively with minimal morbidity in selected patients.

Whole-eye transplantation: a look into the past and vision for the future.

Blindness afflicts ~39 million people worldwide. Retinal ganglion cells are unable to regenerate, making this condition irreversible in many cases. Whole-eye transplantation (WET) provides the opportunity to replace diseased retinal ganglion cells, as well as the entire optical system and surrounding facial tissue, if necessary. Recent success in face transplantation demonstrates that this may be a promising treatment for what has been to this time an incurable condition. An animal model for WET must be established to further enhance our knowledge of nerve regeneration, immunosuppression, and technical aspects of surgery. A systematic review of the literature was performed to evaluate studies describing animal models for WET. Only articles in which the eye was completely enucleated and reimplanted were included. Study methods and results were compared. In the majority of published literature, WET can result in recovery of vision in cold-blooded vertebrates. There are a few instances in which mammalian WET models demonstrate survival of the transplanted tissue following neurovascular anastomosis and the ability to maintain brief electroretinogram activity in the new host. In this study we review in cold-blooded vertebrates and mammalian animal models for WET and discuss prospects for future research for translation to human eye transplantation.

Unusual Volar Pulp Location of Glomus Tumor

Summary: Glomus tumors are benign, painful growths originating from glomus bodies and comprise just 1% of tumors arising in the hand, with fewer than 10% in the volar pulp of digits. Hallmark symptoms of glomus tumors include hypersensitivity to cold, heightened pinprick sensitivity, and paroxysmal pain. We report a 72-year-old, right-hand dominant man who presented with pain in the left middle finger, localized to the tip. The fingertip was incredibly sensitive to touch, and his pain increased at night. He reported no recollection of trauma. Palpation of the finger revealed no mass, although it did indicate a focal point of pain within the distal pulp of the digit. Magnetic resonance imaging of the left hand revealed a round 7.0 × 4.0 × 6.0-mm soft tissue lesion along the volar ulnar aspect of the distal third digit. An incision was made in the mid-axial plane, circumscribing and removing the mass bluntly. It was a tan-yellow, soft tissue nodule of 0.8-cm in diameter without stalk or adherences to joints. Pathology revealed the mass was a glomus tumor. Symptoms improved on removal, and he healed without complication. Glomus tumors in the volar digital pulp can be difficult to diagnose. However, the presence of localized pain in the fingertip was reason to consider glomus tumor and proceed with treatment. Complete surgical removal of a glomus tumor is necessary to resolve symptoms and prevent recurrence.

An Elastomeric Polymer Matrix, PEUU-Tac, Delivers Bioactive Tacrolimus Transdurally to the CNS in Rat

Central nervous system (CNS) neurons fail to regrow injured axons, often resulting in permanently lost neurologic function. Tacrolimus is an FDA-approved immunosuppressive drug with known neuroprotective and neuroregenerative properties in the CNS. However, tacrolimus is typically administered systemically and blood levels required to effectively treat CNS injuries can lead to lethal, off-target organ toxicity. Thus, delivering tacrolimus locally to CNS tissues may provide therapeutic control over tacrolimus levels in CNS tissues while minimizing off-target toxicity. Herein we show an electrospun poly(ester urethane) urea and tacrolimus elastomeric matrix (PEUU-Tac) can deliver tacrolimus trans-durally to CNS tissues. In an acute CNS ischemia model in rat, the optic nerve (ON) was clamped for 10s and then PEUU-Tac was used as an ON wrap and sutured around the injury site. Tacrolimus was detected in PEUU-Tac wrapped ONs at 24 h and 14 days, without significant increases in tacrolimus blood levels. Similar to systemically administered tacrolimus, PEUU-Tac locally decreased glial fibrillary acidic protein (GFAP) at the injury site and increased growth associated protein-43 (GAP-43) expression in ischemic ONs from the globe to the chiasm, consistent with decreased astrogliosis and increased retinal ganglion cell (RGC) axon growth signaling pathways. These initial results suggest PEUU-Tac is a biocompatible elastic matrix that delivers bioactive tacrolimus trans-durally to CNS tissues without significantly increasing tacrolimus blood levels and off-target toxicity.