Sakir Unal

A cadaver study in preparation for facial allograft transplantation in humans Part II. Mock facial transplantation

Background: The authors have performed mock facial transplantation by harvesting total facial-scalp flaps from donors and transferring them to recipient cadavers. Methods: A total of 10 fresh human cadavers were dissected. In the donor, the authors have measured the time of facial-scalp flap harvesting, and the length of the arterial and venous pedicles and sensory nerves that were included in the facial flaps. In the recipient, the authors have evaluated the time of facial skin harvest as a monobloc full-thickness graft, the anchoring regions for the inset of the donor facial flaps, and the time sequences for the vascular pedicle anastomoses and nerve coaptations. Results: In the donor cadaver, the mean harvesting time of the total facial-scalp flap harvest was 235.62 ± 21.94 minutes. The mean length of the supraorbital, infraorbital, mental, and great auricular nerves was 1.5 ± 0.15, 2.46 ± 0.25, 3.02 ± 0.31, and 6.11 ± 0.42 cm, respectively. The mean length of the external carotid artery, the facial vein, and external jugular vein was 5 ± 0.32, 3.15 ± 0.32, and 5.78 ± 0.5 cm, respectively. In the recipient cadaver, the mean harvesting time of facial skin as a monobloc full-thickness graft was 47.5 ± 3.53 minutes. The mean time for the preparation of the arterial and venous pedicles and sensory nerves for the future anastomoses and coaptation was 30 ± 0 minutes. The mean time for facial flap anchoring was 22.5 ± 3.53 minutes. The total mean time of facial mock transplantation without vessels and nerve repair was 320 ± 7.07 minutes (5 hours 20 minutes). Conclusion: Based on anatomical dissections in this cadaver study, the authors have estimated the time and sequence of facial flap harvest and inset to mimic the clinical scenario of the facial transplantation procedure.

New surgical approach in facial transplantation extends survival of allograft recipients

We have previously developed a composite total face–scalp allotransplantation model based on bilateral common carotid arteries (CCA) and external jugular veins. To decrease the mortality rates, different modifications of arterial anastomoses in the facial allograft recipients are presented. Eighteen full face–scalp allograft transplantations were performed across major histocompatibility (MHC) barriers between ACI (RT1a) donors and Lewis (RT11) recipients. Bilateral CCA and bilateral external carotid arteries of the recipients were used as recipient vessels to vascularize the flap in 5 and 4 transplants, respectively. In 9 transplants, unilateral CCA of the recipients were used to vascularize the face/scalp flap. All the animals received CsA 16 mg/kg/d Sc, which was tapered over 4 weeks to 2 mg/kg/d. In transplants utilizing bilateral CCA, the survival rate of the animals was very short. Transplants in which unilateral CCA were used yielded 100% survivals over 200 days posttransplant. These modifications of arterial anastomoses have significantly improved survival of facial allograft recipients.

Composite hemiface/calvaria transplantation model in rats

Background: Extensive craniomaxillofacial deformities including bone and soft-tissue defects are always challenging for reconstructive surgeons. The purpose of this study was to extend application of the face/scalp transplantation model in the rat by incorporation of the vascularized calvarial bone, based on the same vascular pedicle, as a new treatment option for extensive craniomaxillofacial deformities with large bone defects. Methods: Seven composite hemiface/calvaria transplantations were performed across major histocompatibility complex barrier between Lewis-Brown Norway and Lewis rats. Seven donor and seven recipient rats were used in this study. Hemicalvarial bone and face grafts were dissected on the same pedicle of the common carotid artery and jugular vein and were transplanted to the deepithelialized donor faces. All rats received tapered and continuous doses of cyclosporine A monotherapy. Evaluation methods included flap angiography, daily inspection, computed tomographic scan, and bone histology. Results: Flap angiography demonstrated the vascular supply of the bone. The average survival time was 154 days. There were no signs of rejection and there was no flap loss noted at 220 days posttransplantation. Bone histology at days 7, 30, 63, and 100 after transplantation revealed viable bone at all time points, and computed tomographic scans taken at days 14, 30, and 100 revealed normal bones without resorption. Conclusions: For extensive face deformities involving large bone and soft-tissue defects, this new osteomusculocutaneous hemiface/calvaria flap model may serve to create new reconstructive options for covering during one surgical procedure.

Analysis of skin-graft loss due to infection: infection-related graft loss.

This prospective study was performed to analyze the causes of infection-related skin-graft loss in a general population of plastic and reconstructive surgery patients. One hundred thirty-two patients who received either full- or split-thickness skin grafts to reconstruct soft-tissue defects were included. The tissue defects were grouped according to the cause as follows: vascular ulcers (9.2%), burns (14.5%), traumatic tissue defects (36.6%), and flap donor-site defects (39.7%). In all cases, the preoperative evaluation indicated an adequate wound-bed preparation. However, graft loss secondary to infection was recorded in 31 patients (23.5%). The microbiological cultures revealed Pseudomonas aeruginosa in 58.1% of the cases (P < 0.05), followed by Staphylococcus aureus, Enterobacter, enterococci, and Acinetobacter; 58.3% of grafts in vascular ulcers, 47.4% of grafts in burns, 16.7% of grafts in traumatic-tissue defects; and 13.5% of grafts in donor-site defects were lost due to infection. Vascular ulcers and burns were more commonly associated with graft losses due to infection than other tissue defects (P < 0.001). No correlation was found between the etiological cause of the defects and the microorganisms cultured. However, Pseudomonas infections were more fulminant and caused an increased reoperation rate 4.2 times (P < 0.05). Full-thickness grafts were more resistant to infection than split-thickness grafts (P<0.05). Graft loss due to infection was also more common in grafts applied to the lower extremities or when performed at multiple sites. In conclusion, 23.7% of skin grafts were lost due to infection in a group of general plastic surgery patients. Infection-related graft loss was more commonly encountered in vascular ulcers and burn wounds, and the most common cause was Pseudomonas aeruginosa.

Hematopoietic Stem Cell Engraftment and Seeding Permits Multi‐Lymphoid Chimerism in Vascularized Bone Marrow Transplants

Vascularized bone marrow transplantation (VBMT) across a MHC barrier under a 7‐day αβ‐TCR mAb and CsA protocol facilitated multiple hematolymphoid chimerism via trafficking of the immature (CD90) bone marrow cells (BMC) between donor and recipient compartments. Early engraftment of donor BMC [BN(RT1n)] into the recipient BM compartment [LEW(RT1l)] was achieved at 1 week posttransplant and this was associated with active hematopoiesis within allografted bone and correlated with high chimerism in the hematolymphoid organs. Two‐way trafficking between donor and recipient BM compartments was confirmed by the presence of recipient MHC class I cells (RT1l) within the allografted bone up to 3 weeks posttransplant. At 10 weeks posttransplant, decline of BMC viability in allografted bone corresponded with bone fibrosis and lack of hematopoiesis. In contrast, active hematopoiesis was present in the recipient bone as evidenced by the presence of donor‐specific immature (CD90/RT1n) cells, which correlated with chimerism maintenance. Clonogenic activity of donor‐origin cells (RT1n) engrafted into the host BM compartment was confirmed by colony‐forming units (CFU) assay. These results confirm that hematolymphoid chimerism is developed early post‐VBMT by T‐cell lineage and despite allografted bone fibrosis chimerism maintenance is supported by B‐cell linage and active hematopoiesis of donor‐origin cells in the host BM compartment.

Surgical treatment of urethral fistulas following hypospadias repair.

&NA; Development of urethral fistulas is one of the most common late complications of hypospadias surgery. A total of 161 male patients who had 186 urethrocutaneous fistulas were first classified according to the fistula classification of Horton and colleagues and then treated with three types of procedures: simple closure, local rotation flaps, or tube graft reconstruction. With initial surgical intervention, 156 of 186 fistulas were treated successfully. The remaining 30 fistulas (16.1%) recurred during the follow‐up period. In the recurrent cases, immediate closure was not preferred, and an average of 6 months was waited before considering any additional surgical attempt. Distal cases had a higher failure rate, and the simple closure technique failed to show a success rate as high as local flap or tube graft repair. The high recurrence of distal cases was attributed mainly to the lack of adequate soft tissue adjacent to the fistula, which is vital for safe closure. In addition, the traction effect of erection on the skin and urethra, which is more prominent distally than proximally, is also believed to play an additive role. To increase success, the selection of appropriate treatment modality and customization of techniques for each patient cannot be overemphasized. However, the authors conclude that careful presurgical assessment of the patient, a 6‐month delay before any secondary surgical attempt, inversion of the urethral mucosa, avoidance of any overlapping suture lines, urinary diversion proximal to the repair site for 5 to 11 days, and usage of thin, absorbable suture materials are the main criteria that should be met for a satisfactory hypospadias fistula repair. Latifoğlu O, Yavuzer R, Ünal Ŝ, Çavuşoğlu T, Atabay K. Surgical treatment of urethral fistulas following hypospadias repair. Ann Plast Surg 2000;44: 381‐386

The effect of gradually increased blood flow on ischemia-reperfusion injury.

Even with excellent operative techniques, prolonged ischemic periods may cause unwanted results because of a complex mechanism called reperfusion injury. Various pharmacological and immunological agents have been used to prevent this type of injury. Another known way to diminish reperfusion injury is the gradual reperfusion of the ischemic tissues. In this study, the effect of a gradual increase in blood flow on ischemia-reperfusion injury of the skeletal muscle was investigated. The right hind limbs of 15 rats were partially amputated, leaving the femoral vessels intact. Preischemic femoral arterial blood flow was measured by using a transonic small-animal blood flowmeter (T106) in all animals. The rats were divided into three groups: Group I consisted of control rats; no ischemia was induced. Group II was the conventional clamp release group. Clamps were applied to the femoral vessels to induce 150 minutes of ischemia. The clamps were then released immediately and postischemic blood flow was measured. Group III was the gradual clamp release group. After 150 minutes of ischemia, clamps were released gradually at a rate so that the blood flow velocity would reach one fourth the mean preischemic value at 30 seconds, one half at 60 seconds, three fourths at 90 seconds, and would reach its preischemic value at 120 seconds. Total clamp release was allowed when blood flow was less than 1.5 fold of the preischemic values. Postoperatively the soleus muscles were evaluated histopathologically, and malonyldialdehyde and myeloperoxidase levels were measured. The mean preischemic blood flow was 13.6 ± 2.24 ml per kilogram per minute in all groups. In the conventional release group, postischemic flow reached four to five fold its preischemic values (61.06 ml per kilogram per minute). Histopathology revealed more tissue damage in the conventional release group. Malondialdehyde and myeloperoxidase levels were also significantly lower in the gradual release group. Depending on histological and biochemical findings, a gradual increase in blood flow was demonstrated to reduce the intensity of ischemia-reperfusion injury in the soleus muscle of this animal model.Ünal Ş, Özmen S, Demİr Y, et al. The effect of gradually increased blood flow on ischemia-reperfusion injury. Ann Plast Surg 2001;47:412–416

The effects of carnitine on distally-burned dorsal skin flap: an experimental study in rats

OBJECTIVE In ischemia and burn injuries, there are major alterations threatening tissue survival. Increased energy flow requirements are among the major problems in these disorders. Carnitine is an endogenous cofactor, which has a regulatory action on the energy flow from different oxidative sources. The purpose of this study was to determine the effects of carnitine in an experimental flap model. Biochemically, nitric oxide (NO), malondialdehyde (MDA), and acetylcholinesterase levels, and histopathologically tissue examination under light microscope were studied. METHODS In the rat dorsal skin, a 10 cm x 3 cm flap was marked. The most distal 3 cm x 3 cm of the flap was burned to full-thickness. The dorsal flap was elevated, and sutured back to its original site. Sixteen rats were divided into two groups (a control (1) and a study group (2)), consisting of eight rats in each. While the animals in the control group were just followed, the animals in the study group were administrated carnitine with a dose of 100 mg/kg per day for 7 days. RESULTS At the end of the experiment: the mean surviving areas of the flaps were 15.22 cm(2) (50.73%) in group 1, 20.53 cm(2) (68.43%) in group 2, and the difference was statistically significant (P=0.008). In the analysis of blood samples; the mean levels of NO were 22.63 and 40.78 micromol/l; of MDA were 6.74 and 3.79 ng/ml; and of acetylcholinesterase were 136.14 and 222.85 U/l in groups 1 and 2, respectively. The differences in the levels of NO (P=0.001), MDA (0.027) and acetylcholinesterase (P=0.006) were statistically significant. Histopathological examination revealed a full-thickness muscle necrosis in addition to skin tissue in the control group, while healing tissue was present with marked cellularity including mixed inflammatory cells and fibroblast proliferation with an increased vascularity in the form of capillary budding in the study group. CONCLUSION Carnitine has a positive effect in such a model, particularly in preventing the progressive effect of burn, and limiting the necrosis in the full-thickness burned part.

Comparison of ischemic and chemical preconditioning in jejunal flaps in the rat.

Jejunum is one of the most frequently used free flaps in esophagus reconstruction. However, the sensitivity of intestinal tissue to ischemia decreases the margin of safety of this donor site while increasing the risk of postoperative complications such as fistula formation and stenosis. Ischemic preconditioning can increase the tolerance of jejunal tissue to ischemia. In this study, the authors investigated the effects of chemical preconditioning with adenosine infusion on ischemia reperfusion injury in the rat jejunum, and evaluated the presence of any additive effects of adenosine administration when used together with ischemic preconditioning. Forty Sprague-Dawley rats weighting 200 to 250 mg were used in the study. Rats were randomly divided into five groups. In group I (sham-operated controls), only laparotomy was performed. In group II (ischemia-reperfusion injury), the superior mesenteric artery was clamped for 40 minutes to induce ischemia in the small bowel, followed by 60 minutes of reperfusion. In group III (ischemic preconditioning), two cycles of 5-minute ischemia and 5-minute reperfusion were performed before implementation of the ischemia-reperfusion protocol used in group II. In group IV (chemical preconditioning), adenosine (1000 &mgr;g/kg) was infused into the internal jugular vein before the group II ischemia-reperfusion schedule was implemented. In group V (adenosine-enhanced ischemic preconditioning), adenosine (1000 &mgr;g/kg) was infused into the internal jugular vein before ischemic preconditioning, followed by 40 minutes of ischemia and 60 minutes of reperfusion. At the end of the reperfusion period, samples from the jejunum were harvested and myeloperoxidase activity was determined as a measure of leukocyte accumulation. Malondialdehyde levels were measured to assess lipid peroxidation. Histopathologic sections stained with hematoxylin-eosin were evaluated for the presence of mucosal damage according to the Chiu scoring method. Immunohistochemical staining by M30 monoclonal antibodies was performed to quantify the number of ischemia-induced apoptotic cells in the intestinal mucosa. The myeloperoxidase and malondialdehyde levels were significantly lower in groups I, III, IV, and V when compared with group II. Although there were no significant differences among myeloperoxidase and malondialdehyde levels in groups III, IV, and V, group I had significantly lower levels of activity compared with the other three groups. Histological scoring reflected significantly less damage in groups I, III, IV, and V compared with group II. Similarly, the number of apoptotic cells was significantly lower in groups I, III, IV, and V when compared with group II. However, no difference was detected among these four groups with regard to either histopathological scoring or apoptosis numbers. This is the first study showing that adenosine administration is as effective as ischemic preconditioning in inducing ischemic tolerance in the rat jejunum. However, there was no enhancement of ischemic preconditioning with prior adenosine infusion.

Donor–origin cell engraftment after intraosseous or intravenous bone marrow transplantation in a rat model

We compared the effects of intraosseous BMT with those of standard i.v. BMT on the efficacy on donor-cell engraftment into the BM and lymphoid organs across an MHC barrier in rats. Twenty-four intraosseous and 24 i.v. BMTs were performed from 48 ACI (RT1a) donors to 48 Lewis (RT1l) recipients. Each transplant group received either intraosseous or i.v. BMT. Groups I and II served as controls without immunosuppression (n=16); groups III and IV received cyclosporine monotherapy (n=16); and V and VI received αβ-TCR monoclonal antibody and cyclosporine A (αβ-TCR/CsA) for 7 days (n=16). In each group, four rats received 35 × 106 transplanted bone marrow cells (BMCs) and four received 70 × 106 cells. All animals survived without GVHD. Mean (±s.d.) donor-cell engraftment into BM of recipients after intraosseous BMT was 7.9% (±1.3%) in recipients receiving αβ-TCR-CsA and 70 × 106 BMCs, and 4.2% (±1.4%) in recipients after i.v. transplantation. The seeding efficacy of donor cells into lymphoid tissue was greater after intraosseous BMT and αβ-TCR-CsA than after standard i.v. transplantation. In our model, intraosseous BMT facilitated donor-cell engraftment under short-term immunodepletive αβ-TCR/CsA protocol, which resulted in a temporary state of immune unresponsiveness.