Biomedical subjects

Jörg Wefer

Publications and source records attributed to Jörg Wefer.

4 recordsLinked to original sources

PubMed2005

Biological vascularized matrix for bladder tissue engineering: matrix preparation, reseeding technique and short-term implantation in a porcine model.

PURPOSE: We generated a vascularized, autologous, reseeded bladder substitute and evaluated immediate vascularization and perfusion of the graft after implantation to the recipient organism in a porcine model. MATERIAL AND METHODS: Acellular matrix was processed from porcine small bowel segments by subsequent mechanical, chemical and enzymatic decellularization, preserving the jejunal arteriovenous pedicles. In 2 separate steps the matrix was reseeded with primary bladder smooth muscle cells (SMCs) and urothelial cells (UCs), and its vascular structures were resurfaced with endothelial progenitor cells (EPCs). To evaluate graft perfusion short-term implantation was performed. RESULTS: The acellular scaffold was successfully repopulated with multilayers of ingrowing SMCs and superficial UCs. After reseeding the jejunal arteriovenous pedicles with EPCs and cultivation for 3 weeks the larger vessels as well as the intramural scaffold capillary network were repopulated with cell monolayers expressing endothelial specific proteins. Perfusion stagnation and implant thrombosis occurred within 30 minutes after the implantation of acellular scaffolds not reseeded with EPCs. In the EPC reseeded group the vascular system revealed intact perfusion and no relevant thrombus formation was observed after 1 or 3 hours. CONCLUSIONS: The current study of successful SMC and UC reseeding, vessel resurfacing with EPCs and short-term vascular patency represents the promising in vitro and in vivo basis for further evaluation of this biological vascularized matrix in chronic long-term large animal implantation experiments.

Animals↗

PubMed2004

Functional tissue engineering of autologous tunica albuginea: a possible graft for Peyronie's disease surgery.

OBJECTIVES: The aim of the present study was to generate a tissue engineered type of mechanically stable graft suitable for surgical replacement of the tunica albuginea penis. METHODS: Porcine fibroblasts isolated from open fascia biopsies were seeded on decellularized collagen matrices and then cultivated in a bioreactor under continuous multiaxial stress for up to 21 days (n=12). Static cultures without mechanical stress served as controls. Cell proliferation, cell alignment, and de novo synthesis of extracellular matrix proteins (proteoglycans, procollagen I, elastin) in these grafts was evaluated by hematoxylin-eosin, pentachrome, and immuno-staining. Additionally, the enzymatic isolation of porcine fibroblasts from X4mm skin punch biopsies (n=8) was evaluated. RESULTS: Mechanically strained cultures of fibroblasts showed a homogeneous multilayer matrix infiltration and a regular cell alignment in the direction of strain axis after 7 days, as well as a de novo production of extracellular matrix proteins compared to the static control. A large amount of viable fibroblasts was easily obtained from small skin punch biopsies. CONCLUSION: This study shows that continuous multiaxial stimuli improve proliferation and extracellular matrix synthesis of mature fibroblasts reseeded on a biological matrix making this a feasible autologous tissue engineered graft for penile surgery. For the clinical setting fibroblasts harvested from small skin biopsies can be a comfortable cell source.

Animals↗

PubMed2004

Cytotoxicity of different intracavernous vasoactive drugs on cultured endothelial cells of human corpus cavernosum penis.

OBJECTIVES: To investigate the cytotoxic effect of prostaglandin E(1) (PGE(1)), a standard combination of papaverine/phentolamine, and a triple mixture of these agents on human cavernosal endothelial cells using a cell culture model. The endothelial layer of the corpus cavernosum plays an important role in signal transduction of penile erection and is directly exposed to vasoactive agents after intracavernous injection for erectile dysfunction. METHODS: Primary endothelial cells were obtained from the corpus cavernosum of 13 potent patients undergoing penile surgery. Cultured cells were exposed for 30 minutes to physiologic dilutions of 20 microg PGE(1), 30 mg papaverine/1 mg phentolamine, or the same dosages of the triple mixture of these agents, each dissolved in 5 to 50 mL sodium chloride. Lactate dehydrogenase release as a cytotoxicity marker was measured 6 hours after drug exposure, and the total cell metabolic activity was quantified after 48 hours with a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS)-based assay. Additionally, the amount of viable cells was identified with a dual fluorescent staining procedure. RESULTS: The initial release of lactate dehydrogenase was elevated up to 3.2-fold in the concentrated papaverine/phentolamine and triple mixture group compared with PGE(1) and the control. After 48 hours, the papaverine-containing formulations led to a significant dose-dependent decrease in the viable cell count and metabolic activity of the cultures that was not noticed with PGE(1). CONCLUSIONS: These in vitro data strongly suggest an unfavorable effect of vasoactive agents containing papaverine on cavernosal endothelial cells. Before fibrotic changes of the smooth muscle stroma, the functionally important endothelium of the corpus cavernosum might suffer significantly from intracavernous injection therapy. Therefore, papaverine should no longer be used for this indication.

Alprostadil↗

PubMed2003

Androgen and estrogen receptors in the human corpus cavernosum penis: immunohistochemical and cell culture results.

Despite the central and peripheral effects of androgens on the nervous system, the local effects of androgens in the corpus cavernosum penis and their importance for erectile function is still unclear. In this study corpus cavernosum biopsies of eight adult potent patients, aged 19-63 years, undergoing penile deviation surgery (group A) and 12 patients undergoing male-to-female transsexual surgery (group B) were immunostained for nuclear androgen and estrogen-alpha receptors. Additionally, primary corpus cavernosum endothelial cell cultures were obtained from six transsexual patients and exposed to testosterone, dihydrotestosterone, estradiol and progesterone likewise for 7 days. Total cell count was performed and cell metabolic activity was measured by a tetrazolium salt-based assay. Androgen and estrogen-alpha receptors were detected in stromal as well as in endothelial cells. Of all cell nuclei, 74.9% (SD 16.4) in group A and 63.5% (SD 17.1) in group B were positively stained for androgen receptors. The respective percentage of estrogen receptors was 11% (SD 9.5) and 21.2% (SD 12.6). An age-dependent difference in receptor distribution was not observed in either group. In the cell culture system only cultures exposed to testosterone and dihydrotestosterone showed a dose-dependent increase of cell metabolic activity compared to the cultures supplemented with estradiol and progesterone. The significant and age-independent high androgen and low estrogen-alpha receptor distribution found in both groups suggests a possible peripheral effect of androgens at the level of the corpus cavernosum penis in adult humans. This is supported by the observed effect of testosterone and dihydrotestosterone on cell count and endothelial cell metabolism in our cell culture system. The role of estrogens remains unclear.

Adult↗