[New perspectives in skeletal muscle tissue engineering]. / Neue Perspektiven des Skelettmuskel-Tissue-Engineerings.

Due to the enormous expansion of knowledge in the fields of stem cell research and biomaterials, skeletal muscle tissue engineering represents a rapidly developing field of biomedical research. This article provides a general overview of skeletal muscle tissue engineering, including a discussion of recent findings and future research perspectives. Additionally, the results of myogenic differentiation of human mesenchymal stem cells and satellite cells are presented.

[Regenerative medicine in head and neck reconstructive surgery]. / Regenerative Medizin. Chancen für die rekonstruktive Kopf-Hals-Chirurgie.

Autologous transplantation is regarded as the gold standard in the treatment of congenital or acquired deformities. However, the availability of autologous tissue for transplantation is often limited. Regenerative medicine aims to activate individuals' own intrinsic regenerative mechanisms and embraces tissue engineering, cell/system biology, gene therapy and stem-cell biology. Most approaches in tissue engineering are based on the expansion of small autologous cell aggregates. Tissue engineering supplemented by isolated and amplified stem cells is another very promising option for producing autologous transplants and getting over the limited availability. The association of stem cell-based tissue engineering and gene therapy allows the creation of regenerative tissue in the optimal ambience of regulatory proteins. This leads to great opportunities in the transplantation of skin, bones or cartilage. This paper presents the current status and the possible benefits, but also the limitations, of regenerative medicine in reconstructive surgery of the head and neck.

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.

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.