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Biomedical subjects

R E Horch

Publications and source records attributed to R E Horch.

65 records · Page 4Linked to original sources
PubMedDate not supplied

Correction of vitiligo with contralateral areolar skin graft during mammary reduction plasty.

Vitiligo has been reported to be a contraindication against reduction mammaplasty. However, this report shows for the first time that reduction mammaplasty may serve as a means to excise breast vitiligo lesions and to repigment the recipient areola by a contralateral areolar full-thickness skin graft onto the deepidermized recipient areola. The repigmented areolar skin remained stable and cosmetically pleasing for over 4 years by now. There was no vitiligo occurring in the incision lines.

Adult↗
PubMedDate not supplied

Reconstitution of basement membrane after 'sandwich-technique' skin grafting for severe burns demonstrated by immunohistochemistry.

Reconstitution of basement membrane structures after "sandwich-technique" grafting of severe deep burns is demonstrated with use of immunohistochemical techniques. Cryosections of human skin after epifascial burn wound excision and sandwich grafting were stained with monoclonal antibodies against type IV and VII collagen, polyvalent antiserum against type VI collagen, and polyvalent antibody against laminin. Standard hematoxylin and eosin histologies were performed for morphologic correlation. Reorganization of the mesenchymal border zone (basement membrane), after transplantation of extremely expanded split-thickness skin autografts overlaid with glycerolized split-thickness skin allografts onto debrided human full-thickness wounds, occurred from day 5 to day 35. The autografts reepithelize the spaces between the mesh structure, which has been covered primarily exclusively with allogenic skin, and form a layered squamous epithelium, with an underlying three-dimensional basket-weave array of collagen in the remodeled neodermis after epifascial excision. Immunochemical techniques detect the reconstitution of a basement membrane zone with a typical architecture and distribution of laminin, type IV, and type VII collagen being built up 1 week to 5 weeks after sandwich grafting. These structures can be seen in the autografts during the first 2 weeks and are consistent in the whole reconstituted skin after day 35. To our knowledge this is the first report of the expression of type VI collagen in these types of wounds. The findings are compared with the expression of type VI collagen in healthy skin. The results indicate that the modified sandwich-grafting technique is an adequate means for early burn wound closure and resurfacing of third-degree burn wounds and leads to the reconstitution of dermal qualities.

Basement Membrane↗
PubMedDate not supplied

Skeletal muscle tissue engineering.

The reconstruction of skeletal muscle tissue either lost by traumatic injury or tumor ablation or functional damage due to myopathies is hampered by the lack of availability of functional substitution of this native tissue. Until now, only few alternatives exist to provide functional restoration of damaged muscle tissues. Loss of muscle mass and their function can surgically managed in part using a variety of muscle transplantation or transposition techniques. These techniques represent a limited degree of success in attempts to restore the normal functioning, however they are not perfect solutions. A new alternative approach to addressing difficult tissue reconstruction is to engineer new tissues. Although those tissue engineering techniques attempting regeneration of human tissues and organs have recently entered into clinical practice, the engineering of skeletal muscle tissue ist still a scientific challenge. This article reviews some of the recent findings resulting from tissue engineering science related to the attempt of creation and regeneration of functional skeletal muscle tissue.

Animals↗
PubMedDate not supplied

Impact of electrical stimulation on three-dimensional myoblast cultures - a real-time RT-PCR study.

Several focal skeletal muscle diseases, including tumours and trauma lead to a limited loss of functional muscle tissue. There is still no suitable clinical approach for treating such defects. A promising approach could be the tissue engineering of skeletal muscle. However, a clinically reliable differentiation stimulus for three-dimensional (3-D) cultures is necessary for this process, and this condition has not yet been established. In order to quantify and analyze the differentiation potential of electrical cell stimulation, primary myoblasts were stimulated within a 3-D fibrin- matrix. Gene expression of MyoD, myogenin and AChR-epsilon were measured by real-time RT-PCR over a time period of eight days, showing immediate down-regulation of all marker genes. For tissue engineering approaches, cell multiplication is crucial for acquisition of sufficient tissue volumes for reconstruction. Therefore, all experiments were performed with high and low passaged myoblasts, demonstrating higher transcript rates of marker genes in lowpassage cells. Our findings strongly suggest a reconsideration of electrical stimulation in muscle tissue engineering.

Animals↗
PubMedDate not supplied

Tissue engineering of bone: the reconstructive surgeon's point of view.

Bone defects represent a medical and socioeconomic challenge. Different types of biomaterials are applied for reconstructive indications and receive rising interest. However, autologous bone grafts are still considered as the gold standard for reconstruction of extended bone defects. The generation of bioartificial bone tissues may help to overcome the problems related to donor site morbidity and size limitations. Tissue engineering is, according to its historic definition, an "interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function". It is based on the understanding of tissue formation and regeneration and aims to rather grow new functional tissues than to build new spare parts. While reconstruction of small to moderate sized bone defects using engineered bone tissues is technically feasible, and some of the currently developed concepts may represent alternatives to autologous bone grafts for certain clinical conditions, the reconstruction of large-volume defects remains challenging. Therefore vascularization concepts gain on interest and the combination of tissue engineering approaches with flap prefabrication techniques may eventually allow application of bone-tissue substitutes grown in vivo with the advantage of minimal donor site morbidity as compared to conventional vascularized bone grafts. The scope of this review is the introduction of basic principles and different components of engineered bioartificial bone tissues with a strong focus on clinical applications in reconstructive surgery. Concepts for the induction of axial vascularization in engineered bone tissues as well as potential clinical applications are discussed in detail.

Bioartificial Organs↗
PubMedDate not supplied

N-acetyl-L-cysteine abrogates fibrogenic properties of fibroblasts isolated from Dupuytren's disease by blunting TGF-beta signalling.

Dupuytren's disease, a benign fibroproliferative disorder of the palmar fascia, represents an ideal model to study tissue fibrosis. Transforming growth factor-beta1 (TGF-beta1) and its downstream Smad signalling system is well established as a key player during fibrogenesis. Thus, targeting this basic pathomechanism seems suitable to establish new treatment strategies. One such promising treatment involves the substance N-acetyl-L-cysteine (NAC), shown to have antifibrotic properties in hepatic stellate cells and rat fibroblasts. In order to investigate antifibrotic effects of N-acetyl-L-cysteine (NAC), fibroblasts were isolated from surgically resected fibrotic palmar tissues (Dupuytren fibroblasts, DF) and exposed to different concentrations of NAC and recombinant TGF-beta1. Fibroblasts isolated from tendon pulleys served as controls (control fibroblasts, CF). Smad signalling was investigated by a Smad binding element driven reporter gene analysis. Both cell types express TGF-beta1, indicating autocrine signalling in DF and CF. This was confirmed by comparing reporter gene activity from LacZ and Smad7 adenovirus infected cells. NAC treatment resulted in abrogation of Smad mediated signalling comparable to ectopically overexpressed Smad7, even when the cells were stimulated with recombinant TGF-beta1 or ectopically expressed a constitutively active TGF-beta receptor type I. Additionally, NAC dose-dependently decreased expression of three major indicators of impaired fibrotic matrix turnover, namely alpha-smooth muscle actin (alpha-SMA), alpha 1 type I procollagen (Col1A1), and plasminogen activator inhibitor-type I (PAI-1). Our results suggest that TGF-beta signalling and subsequent expression of fibrogenesis related proteins in Dupuytren's disease is abrogated by NAC thus providing a basis for a therapeutic strategy in Dupuytren's disease and other fibroproliferative disorders.

Acetylcysteine↗
PubMedDate not supplied

Evaluation of processed bovine cancellous bone matrix seeded with syngenic osteoblasts in a critical size calvarial defect rat model.

INTRODUCTION: Biologic bone substitutes may offer alternatives to bone grafting procedures. The aim of this study was to evaluate a preformed bone substitute based on processed bovine cancellous bone (PBCB) with or without osteogenic cells in a critical size calvarial defect rat model. METHODS: Discs of PBCB (Tutobone) were seeded with second passage fibrin gel-immobilized syngenic osteoblasts (group A, n = 40). Cell-free matrices (group B, n = 28) and untreated defects (group C; n=28) served as controls. Specimens were explanted between day 0 and 4 months after implantation and were subjected to histological and morphometric evaluation. RESULTS: At 1 month, bone formation was limited to small peripheral areas. At 2 and 4 months, significant bone formation, matrix resorption as well as integration of the implants was evident in groups A and B. In group C no significant regeneration of the defects was observed. Morphometric analysis did not disclose differences in bone formation in matrices from groups A and B. Carboxyfluorescine-Diacetate-Succinimidylester (CFDA) labeling demonstrated low survival rates of transplanted cells. DISCUSSION: Osteoblasts seeded into PBCB matrix display a differentiated phenotype following a 14 days cell culture period. Lack of initial vascularization may explain the absence of added osteogenicity in constructs from group A in comparison to group B. PBCB is well integrated and represents even without osteogenic cells a promising biomaterial for reconstruction of critical size calvarial bone defects.

Animals↗
PubMedDate not supplied

A new approach to tissue engineering of vascularized skeletal muscle.

Tissue Engineering of skeletal muscle tissue still remains a major challenge. Every neo-tissue construct of clinically relevant dimensions is highly dependent on an intrinsic vascularisation overcoming the limitations of diffusion conditioned survival. Approaches incorporating the arteriovenous-loop model might bring further advances to the generation of vascularised skeletal muscle tissue. In this study 12 syngeneic rats received transplantaion of carboxy-fluorescine diacetate-succinimidyl ester (CFDA)-labelled, expanded primary myoblasts into a previously vascularised fibrin matrix, containing a microsurgically created AV loop. As control cells were injected into fibrin-matrices without AV-loops. Intra-arterial ink injection followed by explantation was performed 2, 4 and 8 weeks after cell implantation. Specimens were evaluated for CFDA, MyoD and DAPI staining, as well as for mRNA expression of muscle specific genes. Results showed enhanced fibrin resorption in dependence of AV loop presence. Transplanted myoblasts could be detected in the AV loop group even after 8 weeks by CFDA-fluorescence, still showing positive MyoD staining. RT-PCR revealed gene expression of MEF-2 and desmin after 4 weeks on the AVloop side, whereas expression analysis of myogenin and MHC(embryo) was negative. So far myoblast injection in the microsurgical rat AV loop model enhances survival of the cells, keeping their myogenic phenotype, within pre-vascularised fibrin matrices. Probably due to the lack of potent myogenic stimuli and additionally the rapid resorption of the fibrin matrix, no formation of skeletal muscle-like tissue could be observed. Thus further studies focussing on long term stability of the matrix and the incorporation of neural stimuli will be necessary for generation of vascularised skeletal muscle tissue.

Animals↗
PubMedDate not supplied

Liver fibrogenesis due to cholestasis is associated with increased Smad7 expression and Smad3 signaling.

BACKGROUND/AIMS: Profibrogenic TGF-beta signaling in hepatic stellate cells is modulated during transdifferentiation. Strategies to abrogate TGF-beta effects provide promising antifibrotic results, however, in vivo data regarding Smad activation during fibrogenesis are scarce. METHODS: Here, liver fibrosis was assessed subsequent to bile duct ligation by determining liver enzymes in serum and collagen deposition in liver tissue. Activated hepatic stellate cells were identified by immunohistochemistry and immunoblots for alpha smooth muscle actin. Cellular localization of Smad3 and Smad7 proteins was demonstrated by immunohistochemistry. RTPCR for Smad4 and Smad7 was conducted with total RNA and Northern blot analysis for Smad7 with mRNA. Whole liver lysates were prepared to detect Smad2/3/4 and phospho- Smad2/3 by Western blotting. RESULTS: Cholestasis induces TGF-beta signaling via Smad3 in vivo, whereas Smad2 phosphorylation was only marginally increased. Smad4 expression levels were unchanged. Smad7 expression was continuously increasing with duration of cholestasis. Hepatocytes of fibrotic lesions exhibited nuclear staining Smad3. In contrast to this, Smad7 expression was localized to activated hepatic stellate cells. CONCLUSIONS: Hepatocytes of damaged liver tissue display increased TGF-beta signaling via Smad3. Further, negative feedback regulation of TGF-beta signaling by increased Smad7 expression in activated hepatic stellate cells occurs, however does not interfere with fibrogenesis.

Animals↗
PubMedDate not supplied

Single-cell suspensions of cultured human keratinocytes in fibrin-glue reconstitute the epidermis.

To overcome common disadvantages of standard cultured epidermal sheet grafts (CEG) we have developed a new technique of transplanting cultured human keratinocytes suspended as single cells in a fibrin-glue matrix (Keratinocyte-fibrin-glue suspension-KFGS). In an athymic mouse model with reproducible standardized full thickness wounds this new technique was compared directly to CEG. Reepithelialization was similar in both groups, but reconstitution of the dermo-epidermal junction zone, as shown by electron microscopy and immunohistochemistry was significantly enhanced by the fibrin-glue suspension technique. The new KFGS technique is earlier available than sheet grafts, is able to transfer actively proliferative single keratinocytes, and simplifies the application.

Animals↗