Cultured epithelial autografts in the management of burn injuries: a review of the literature

Introduction. The management of large burn victims has significantly improved in the last decades. Specifically autologous cultured keratinocytes (CEA) overcame the problem of limited donor sites in severely burned patients. Several studies testing CEA's in their burn centers give mixed results on the general outcomes of burn patients. Methods. A review of publications with a minimum of 15 patients per study using CEA for the management of severe burn injury from 1989 until 2011 were recruited by using an online database including Medline, Pub Med and the archives of the medical library of the CHUV in Lausanne. Results. 18 studies with a total of 977 patients were included into this review. Most of the studies did not specify if CEA's were grafted alone or in combination with split thickness skin grafts (STSG) although most of the patients seemed to have received both methodologies in reviewed studies. The mean TBSA per study ranged from 33% to 78% in patients that were grafted with CEA's. Here no common minimum TBSA making a patient eligible for CEA grafting could be found. The definition of the "take rate" is not standardized and varied largely from 26% to 73%. Mortality and hospitalization time could not be shown to correlate with CEA use in all of the studies. As late complications, some authors described the fragility of the CEA regenerated skin. Conclusion. Since the healing of large burn victims demands for a variety of different surgical and non-surgical treatment strategies and the final outcome mainly depends on the burned surface as well as the general health condition of the patient, no definitive conclusion could be drawn from the use of CEA's of reviewed studies. From our own experience, we know that selected patients significantly profit from CEA grafts although cost efficiency or the reduction of mortality cannot be demonstrated on this particular cases.

Extracellular matrix components in peripheral nerve repair: how to affect neural cellular response and nerve regeneration?

Peripheral nerve injury is a serious problem affecting significantly patients' life. Autografts are the "gold standard" used to repair the injury gap, however, only 50% of patients fully recover from the trauma. Artificial conduits are a valid alternative to repairing peripheral nerve. They aim at confining the nerve environment throughout the regeneration process, and providing guidance to axon outgrowth. Biocompatible materials have been carefully designed to reduce inflammation and scar tissue formation, but modifications of the inner lumen are still required in order to optimise the scaffolds. Biomicking the native neural tissue with extracellular matrix fillers or coatings showed great promises in repairing longer gaps and extending cell survival. In addition, extracellular matrix molecules provide a platform to further bind growth factors that can be released in the system over time. Alternatively, conduit fillers can be used for cell transplantation at the injury site, reducing the lag time required for endogenous Schwann cells to proliferate and take part in the regeneration process. This review provides an overview on the importance of extracellular matrix molecules in peripheral nerve repair.

Efficacy And Safety Of Baerveldt Aqueous Shunts In Glaucoma Secondary To Anterior Segment Irradiation, For Uveal Melanoma

Purpose: Elevated IOP is commonly associated with iris and ciliary body melanoma. Traditional management requires the majority of eyes to undergo enucleation. The authors describe the first series of Baerveldt aqueous shunts in eyes with uveal melanoma, treated by total anterior segment irradiation.Methods: 25 consecutive patients with unilateral iris melanoma were prospectively recruited after obtaining informed consent. All patients underwent anterior segment proton beam irradiation, corneal limbal autografts and Baerveldt tube implantation at Jules Gonin Eye Hospital, Lausanne. Postoperative examinations were performed on day 1, weeks 1,3,6,9 and months 3,6,12 and annually thereafter. Success was defined as: IOP </=18mmHg (definition A); IOP </= 21mmHg and 20% reduction in IOP (definition B). All complications were recorded.Results: Mean age was 53; mean follow up, 10.3 months; mean interval to treatment following irradiation, 2.4 years; mean pre-op IOP was 29.9 mmHg; mean post-op IOP 14.1 mmHg; mean pre-op medications 3.0; post-op medications 1.3. Success rates were, definition A: 95%; definition B: 90%. Only11% had minor complications and there were no sight-threatening complications. Aggressive ocular hypertension was observed in the several eyes prior to shunt implantation. Two eyes were enucleated for non-glaucoma related sequelae.Conclusions: Baerveldt aqueous shunts are safe and efficacious following total anterior segment irradiation for uveal melanoma. The novel interdisciplinary approach improved ocular retention rates, offering a promising alternative to current management algorithms.

Exploring epidermal stem cell engraftment

Objective: Cultured autologous epidermal stem cells are used to treat extensively burned patients. However, engraftment is variable and it is fundamental to know 1- how many stem cells survive the stress of transplantation and 2- how many stem cells are needed for long-term self-renewal of the regenerated epidermis. Therefore, we have recapitulated the transplantation of autologous cultured epidermal stem cells in the minipig to investigate the cellular and molecular mechanisms involved in engraftment. Methods: Pig keratinocytes were cultivated according to the protocol used in human epidermal cell therapy. Human surgical procedures were adapted to the pig. Engraftment was evaluated clinically and by histology. The presence of epidermal stem cells was evaluated by clonal analysis. The presence of dividing or apoptotic cells was revealed by Ki67 and cleaved-caspase3 immunostaining respectively. Results: The skin of the pig closely resembles human skin and contains clonogenic keratinocytes that can be serially cultivated, cloned or transduced with a gene encoding GFP (Green Fluorescent Protein) by means of recombinant retroviral vectors. Cultured epidermal autografts can be successfully transplanted and their behavior recapitulate our observations in the human. Our experiments confirm that the number of epidermal stem cells rapidly decreases following transplantation. Most importantly, the regenerated epithelium contains dividing cells but little apoptotic cells, thus indicating that transplanted stem cells are pushed toward differentiation in response to the transplantation procedure. Conclusions: The minipig model is extremely useful to investigate stem cell fate during transplantation in human. Understanding engraftment is crucial to improve cell therapy and to design a more efficient generation of epidermal stem cell based products.

Doublecortin-positive cells in the adult primate cerebral cortex and possible role in brain plasticity and development.

We have demonstrated that cortical cell autografts might be a useful therapy in two monkey models of neurological disease: motor cortex lesion and Parkinson's disease. However, the origin of the useful transplanted cells obtained from cortical biopsies is not clear. In this report we describe the expression of doublecortin (DCX) in these cells based on reverse-transcription polymerase chain reaction (RT-PCR) and immunodetection in the adult primate cortex and cell cultures. The results showed that DCX-positive cells were present in the whole primate cerebral cortex and also expressed glial and/or neuronal markers such as glial fibrillary protein (GFAP) or neuronal nuclei (NeuN). We also demonstrated that only DCX/GFAP positive cells were able to proliferate and originate progenitor cells in vitro. We hypothesize that these DCX-positive cells in vivo have a role in cortical plasticity and brain reaction to injury. Moreover, in vitro these DCX-positive cells have the potential to reacquire progenitor characteristics that confirm their potential for brain repair.

Chronic rejection of allogenic dermal grafts in 73 % TBSA burn patient

Rationale: Allogenic grafts are an excellent way to temporarily cover a wound. It prevents the loss of electrolytes and water, reduces the risk of infection and diminishes pain. Another advantage of the allograft is in circumventing problems such as the morbidity of skin graft donor sites. We present here the case of a patient grafted in 1991 with cultured epidermal autografts (CEA) and allogenic skin transplants on his legs, outlining the risks and potential long-term complications. Methods: The 40-year-old male patient was treated with allogenic Split Thickness Skin Graft (STSG) transplantations, CEA and Cyclosporine-A therapy. Allogenic STSG for lower extremities were harvested from a female HIV-negative organ donor. They were transplanted, de-epithelialized and subsequently covered with CEAs. Cyclosporine-A was administered systemically from the first day following transplantation until three weeks after the last CEAs were placed on the allogenic dermis. Results: Immediate results showed a 90% successful grafting under cyclosporine therapy. However, some lesions were still present 16 months later. The skin was hard with little or no elasticity. Five years after the transplantation there were no more lesions. However, a 10-year follow-up showed new ulcers on both lower extremities. All the skin of the right leg was removed and replaced by STSG from the patient's back. Postoperative results were excellent with a 100% graft take. The anatomopathology showed dermo-hypodermic tissue with fibrosis of the dermis, vasculopathy and chronic ulcers compatible with chronic rejection. Conclusion: While early functional results of the allografts may seem encouraging, their long-term evolution remains uncertain and, in this case, presents complications. The apparent antigenic effect of the dermal tissue may be controlled with long-term immunosuppression which may cause important secondary effects. Even with such treatments, 15 years after organ transplantation, about 35% of a transplant is no longer functional. It is therefore important to take these long-term observations into consideration when treating sensitive areas such as hands or a face.

Free microvascular iliac crest flap for extensive talar necrosis--case report with a 16-year long-term follow up.

Atraumatic osteonecrosis of the talus can be extremely painful and lead to significant functional impairment. Although clinical, radiographic, and demographic characteristics of atraumatic osteonecrosis of the talus have been well documented, the diagnosis is frequently missed or delayed; the most common causes are use of corticosteroids and the presence of immune disorders. Operative treatment of large osteochondral lesions of the talus is difficult because the blood supply is poor in the talar dome. Microvascular reconstruction of the talar dome with iliac crest autografts is a complex but functionally excellent therapeutic option. We present a 48-year-old man, who developed an extensive atraumatic avascular necrosis of the talar dome without collapse. Except for insulin dependent diabetes mellitus no further comorbidities were known. A microvascular iliac crest bone flap was inserted into the talus. A follow-up 16 years postoperatively showed a clinically as well as radiographically stable reconstruction of the talar dome and an excellent mobility of the ankle joint. The AOFAS hindfoot scale had improved from initially 33 points to 100 on the last follow-up. Free microvascular bony reconstruction of the talar dome should not only be considered in younger patients but also for middle aged active patients, since our follow-up shows an excellent long term result. Early reconstruction can prevent collapse of the talar bone.

Long-term in vivo regeneration of peripheral nerves through bioengineered nerve grafts.

Although autologous nerve graft is still the first choice strategy in nerve reconstruction, it has the severe disadvantage of the sacrifice of a functional nerve. Cell transplantation in a bioartificial conduit is an alternative strategy to improve nerve regeneration. Nerve fibrin conduits were seeded with various cell types: primary Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC). Two further control groups were fibrin conduits without cells and autografts. Conduits were used to bridge a 1 cm rat sciatic nerve gap in a long term experiment (16 weeks). Functional and morphological properties of regenerated nerves were investigated. A reduction in muscle atrophy was observed in the autograft and in all cell-seeded groups, when compared with the empty fibrin conduits. SC showed significant improvement in axon myelination and average fiber diameter of the regenerated nerves. dASC were the most effective cell population in terms of improvement of axonal and fiber diameter, evoked potentials at the level of the gastrocnemius muscle and regeneration of motoneurons, similar to the autografts. Given these results and other advantages of adipose derived stem cells such as ease of harvest and relative abundance, dASC could be a clinically translatable route towards new methods to enhance peripheral nerve repair.

Human epidermal cultures screened for residual murine feeder cells-No contaminants found

Rationale: Human keratinocytes used for transplants are cultivated on a feeder layer which may be composed of autologous human fibroblasts or 3T3 murine fibroblasts. Using the latter method spares 15 additional days of preparation. In this study we investigate the potential presence of residual murine feeder cell contaminants in epidermal cultures prepared for transplantation. Methods: Monolayers of cultured 3T3-J2 murine fibroblasts were treated with 4 μg/mL of mitomycin C (MMC) for 2 h and used to track cell survival kinetics. Using similar 3T3 cells, human keratinocyte cultures were grown following a modified protocol based on the method described by Rheinwald and Green. Cell sheets were mechanically detached and rinsed 4 times following the same procedure used for transplant preparation. The elimination of 3T3 cells during culture was visually tracked using phase contrast microscopy. Epidermal cultures were then dissociated to produce cell suspensions and analyzed by flow cytometry using a murine-specific antibody, CD90, conjugated to a fluorescein isothiocyanate (FITC) marker. Dead cells were identified using 7-amino-actinomysin D (7-AAD) which binds to DNA in permeabilized cells. Results: 3T3 cells treated with MMC display clear morphological signs of apoptosis, disappearing completely in 9-10 days following kinetics similar to 30 Gy gamma irradiated 3T3 cells. Histological analysis of cultured epidermal sheets revealed homogenous keratinocytic tissue with no 3T3 cells. MMC treated and untreated 3T3 cells displayed strong CD90 expression. Cell suspensions obtained from epidermal cultures were, however, negative for that marker. Conclusion: Results obtained demonstrate the absence of contaminating murine 3T3 feeder cells in human keratinocyte cultures. These findings highlight our success in developing cultured human epidermal autografts.