Rick Cowan

COCULTURE OF BLADDER UROTHELIAL AND SMOOTH MUSCLE CELLS ON SMALL INTESTINAL SUBMUCOSA: POTENTIAL APPLICATIONS FOR TISSUE ENGINEERING TECHNOLOGY

PURPOSE Small intestinal submucosa is a xenogenic, acellular, collagen rich membrane with inherent growth factors that has previously been shown to promote in vivo bladder regeneration. We evaluate in vitro use of small intestinal submucosa to support the individual and combined growth of bladder urothelial cells and smooth muscle cells for potential use in tissue engineering techniques, and in vitro study of the cellular mechanisms involved in bladder regeneration. MATERIALS AND METHODS Primary cultures of human bladder urothelial cells and smooth muscle cells were established using standard enzymatic digestion or explant techniques. Cultured cells were then seeded on small intestinal submucosa at a density of 1 x 105 cells per cm.2, incubated and harvested at 3, 7, 14 and 28 days. The 5 separate culture methods evaluated were urothelial cells seeded alone on the mucosal surface of small intestinal submucosa, smooth muscle cells seeded alone on the mucosal surface, layered coculture of smooth muscle cells seeded on the mucosal surface followed by urothelial cells 1 hour later, sandwich coculture of smooth muscle cells seeded on the serosal surface followed by seeding of urothelial cells on the mucosal surface 24 hours later, and mixed coculture of urothelial cells and smooth muscle cells mixed and seeded together on the mucosal surface. Following harvesting at the designated time points small intestinal submucosa cell constructs were formalin fixed and processed for routine histology including Masson trichrome staining. Specific cell growth characteristics were studied with particular attention to cell morphology, cell proliferation and layering, cell sorting, presence of a pseudostratified urothelium and matrix penetrance. To aid in the identification of smooth muscle cells and urothelial cells in the coculture groups, immunohistochemical analysis was performed with antibodies to alpha-smooth muscle actin and cytokeratins AE1/AE3. RESULTS Progressive 3-dimensional growth of urothelial cells and smooth muscle cells occurred in vitro on small intestinal submucosa. When seeded alone urothelial cells and smooth muscle cells grew in several layers with minimal to no matrix penetration. In contrast, layered, mixed and sandwich coculture methods demonstrated significant enhancement of smooth muscle cell penetration of the membrane. The layered and sandwich coculture techniques resulted in organized cell sorting, formation of a well-defined pseudostratified urothelium and multilayered smooth muscle cells with enhanced matrix penetration. With the mixed coculture technique there was no evidence of cell sorting although matrix penetrance by the smooth muscle cells was evident. Immunohistochemical studies demonstrated that urothelial cells and smooth muscle cells maintain the expression of the phenotypic markers of differentiation alpha-smooth muscle actin and cytokeratins AE1/AE3. CONCLUSIONS Small intestinal submucosa supports the 3-dimensional growth of human bladder cells in vitro. Successful combined growth of bladder cells on small intestinal submucosa with different seeding techniques has important future clinical implications with respect to tissue engineering technology. The results of our study demonstrate that there are important smooth muscle cell-epithelial cell interactions involved in determining the type of in vitro cell growth that occurs on small intestinal submucosa. Small intestinal submucosa is a valuable tool for in vitro study of the cell-cell and cell-matrix interactions that are involved in regeneration and various disease processes of the bladder.

Bladder Regeneration with Cell-Seeded Small Intestinal Submucosa

This study was performed to determine the regenerative properties of smooth muscle cells (SMCs) and urothelial cells (UCs) seeded on small intestinal submucosa (SIS), utilizing a nude mouse model. Human bladder SMCs and UCs were seeded on SIS in a layered coculture fashion. Cell-seeded SIS grafts (1 x 1 cm(2)) were maintained in a CO(2) incubator for 14 days and subsequently folded with the seeded cells facing the lumenal side and implanted subcutaneously into the flanks of nude mice (n = 20). Unseeded SIS grafts were implanted into the contralateral flanks of the mice to serve as controls. Grafts were harvested at 4, 8, and 12 weeks after implantation. By 12 weeks, layered urothelium with a central lumen was noted with early smooth muscle bundle formation peripherally. At each time point, the regenerated SMCs stained positive for alpha-smooth muscle actin, and the UCs stained positive for cytokeratin AE1/AE3. The control group demonstrated no evidence of organized bladder regeneration. This study demonstrates the potential for cell-seeded SIS to induce organized bladder regeneration in vivo. This also provides the basis for additional work utilizing seeded SIS grafts for bladder augmentation.

CHARACTERIZATION OF CULTURED BLADDER SMOOTH MUSCLE CELLS: ASSESSMENT OF IN VITRO CONTRACTILITY

PURPOSE The contractile properties of in vitro cultured bladder smooth muscle cells (SMC) are unknown. This study characterized the in vitro contractile response of human and rat bladder SMC to several pharmacological agonists known to induce in vivo contraction of intact bladder muscle. MATERIALS AND METHODS Human and rat bladder SMC were seeded separately within attached collagen lattices. Contractility of SMC was analyzed by measuring alterations in lattice diameter after exposure and release to the following contractile agonists: carbachol (10(-7)-10(-3) microM), calcium-ionophore (10 microM), lysophosphatidic acid (LPA) (1 microM), endothelin (0.1 microM), KCl (3.33 mmicroM) angiotensin II (10 microM), and serotonin (100 microM). Results were recorded as a mean reduction of the lattice diameter. In addition, immunohistochemical analysis for phenotypic markers of smooth muscle cell differentiation was performed on bladder SMC cultured within collagen lattices. Human palmar fascia fibroblasts, which have been previously well characterized by in vitro contractility and immunohistochemistry, were tested in parallel and used as controls for all the above experiments. RESULTS Human SMC had significant contractile responses to calcium-ionophore (31% +/- 4 relative percent contraction, p <0.05), LPA (34% +/- 4, p <0.05), and endothelin (37 +/- 5%, p <05). There was no significant contraction in response to carbachol, angiotensin II, KCl, or serotonin. Rat bladder SMC had a similar contractile response but did not contract in response to endothelin. In contrast to human and rat bladder SMC, fibroblasts did not contract to calcium-ionophore. CONCLUSIONS In vitro cultured bladder SMC demonstrate loss of contractile response to normal in vivo pharmacologic agonists. Both human and rat bladder SMC can be distinguished in vitro from fibroblasts based upon their lack of contractile response to calcium- ionophore. These results demonstrate the ability to further characterize cultured bladder SMC with in vitro contractility. Further characterization is essential if we are to advance our understanding of the clinical applicability of in vitro studies utilizing cultured bladder SMC.

5α-Androstane-3α,17β-diol activates pathway that resembles the epidermal growth factor responsive pathways in stimulating human prostate cancer LNCaP cell proliferation

5α-Androstane-3α,17β-diol (3α-diol) is considered to have no androgenic effects in androgen target organs unless it is oxidized to 5α-dihydrotestosterone (5α-DHT). We used microarray and bioinformatics to identify and compare 3α-diol and 5α-DHT responsive gene in human prostate LNCaP cells. Through a procedure called ‘hypervariable determination’, a similar set of 30 responsive genes involving signal transduction, transcription regulation, and cell proliferation were selected in 5α-DHT-, 3α-diol-, and epidermal growth factor (EGF)-treated samples. F-means cluster and networking procedures showed that the responsive pattern of these genes was more closely related between 3α-diol and EGF than between 5α-DHT and 3α-diol treatments. We conclude that 3α-diol is capable of stimulating prostate cell proliferation by eliciting EGF-like pathway in conjunction with androgen receptor pathway.