Intestinal muscle undergoes stretch intermittently during peristalsis and persistently proximal to obstruction. The influence of this pervasive biomechanical force on developing smooth muscle cell function remains unknown. We adapted a novel in vitro system to study whether stretch modulates transforming growth factor-beta1 (TGF-beta1) and type I collagen protein and component alpha1 chain [alpha1(I) collagen] expression in fetal human intestinal smooth muscle cells. Primary confluent cells at 20-wk gestation, cultured on flexible silicone membranes, were subjected to two brief stretches or to 18 h tonic stretch. Nonstretched cultures served as controls. TGF-beta1 protein was measured by ELISA and type I collagen protein was assayed by Western blot. TGF-beta1 and alpha1(I) collagen mRNA abundance was determined by Northern blot analysis, quantitated by phosphorimaging, and normalized to 18S rRNA. Transcription was examined by nuclear run-on assay. Tonic stretch increased TGF-beta1 protein 40%, type I collagen protein 100%, TGF-beta1 mRNA content 2.16-fold, and alpha1(I) collagen mRNA 3.80-fold and enhanced transcription of TGF-beta1 and alpha1(I) collagen by 3.1- and 4.25-fold, respectively. Brief stretch stimulated a 50% increase in TGF-beta1 mRNA content but no change in alpha1(I) collagen. Neutralizing anti-TGF-beta1 ablated stretch-mediated effects on alpha1(I) collagen. Therefore, stretch upregulates transcription for TGF-beta1, which stimulates alpha1(I) collagen gene expression in smooth muscle from developing gut.

The purpose of this investigation was to assess the applicability of living-related liver transplantation in an established regional transplant program by determining the frequency of acceptable living donors from an unselected population of pediatric transplant candidates and identify specific factors limiting application of this technique. During the period May 1992 to May 1994, all children accepted as transplant candidates at the University of California-San Francisco were evaluated for potential living-related liver transplantation. Indications for transplantation and patient demographics represented the spectrum anticipated at a regional center. Donor evaluation was performed using a three-phase evaluation process we have previously reported. Retrospective analysis identified 75 potential donors for 38 pediatric candidates (age range, 17 days to 14.5 years; mean, 5.1 years). Twenty-three percent of potential donors declined evaluation. Of the 75 potential donors, only 10 (13%) were found to be acceptable for donation. The leading causes for donor declination were significant medical history (23%), ABO blood group incompatibility (23%), and psychosocial history (20%). Of the 38 recipient candidates, 9 (23%) were offered living-donor transplantation. Five patients have received living-donor transplantation, and 4 patients await the procedure when medical indications exist. Seventy-seven percent of recipient candidates received or are awaiting cadaveric transplantation. These results suggest that current donor criteria markedly limit the application of living-related liver transplantation. (HEPATOLOGY 1995;22:1122-1126 Liver transplantation is now the standard of care in both adult and pediatric patients afflicted with acute or chronic end-stage liver disease. In past years, the disproportionately high mortality rate observed in chil- dren as compared with adults awaiting liver transplantation reflected the disparity between pediatric organ demand and donor supply.' The technique of surgical reduction of cadaveric livers for the treatment of children (reduced-size liver transplantation) has lowered this di~parity.'.~ However, the rapid increase in the number of adult candidates requiring liver transplantation has created a global organ shortage affecting both children and adults.8 Living-related liver transplantation (LRLT) was introduced in anticipation of the current scarcity and is an established, highly effective therapy for ~hildren.~,'-'~ LRLT offers several immediate and theoretical advantages that benefit both the individual and community of recipients. Intensive medical screening of the donor selects for an optimal graft, which, using current surgical techniques that avoid warm ischemia, has a lower risk of primary graft n o n f u n~t i o n .~~' '~~'~~~ Fu rthermore, procurement as an elective procedure provides flexibility in medical timing for transplantation. Strong et all' reported the first successful living donation, and Broelsch et a1 were the first group to establish a living donor transplant ...

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The extracellular matrix influences organogenesis by modulating cell behavior. In humans, collagen is the major matrix constituent of the adult intestinal wall and is synthesized by smooth muscle cells. The objective of the current study was to examine collagen production by fetal human intestinal smooth muscle cells isolated during intestinal morphogenesis. Techniques were developed for the isolation and culture of human fetal intestinal smooth muscle cells. The cultured cells were confirmed as muscle by immunohistochemical stains for cytoskeletal filaments and documentation of contractile behavior. In culture, these cells stained for mesenchymal and muscle cytoskeletal proteins: vimentin, actin, and desmin, and did not stain for neural or epithelial markers. The muscle cells contracted in response to acetylcholine, in contrast to human fetal dermal fibroblasts which did not contract appreciably. Collagen production was assayed by the uptake of [3H]-proline into collagenase-digestible protein. Collagen production was greatest at 11 weeks gestation, the youngest age studied. By 20 weeks gestation, collagen production had decreased to adult levels. However, when compared to another matrix-producing fetal mesenchymal cell, the dermal fibroblast, intestinal smooth muscle cells produced twice as much collagen. Collagen types were determined by polyacrylamide slab gel electrophoresis. Smooth muscle cells predominantly produced types I and III collagen alpha chains. Therefore, collagen production is a significant function of human fetal intestinal smooth muscle cells, and probably plays a major role in the development of intestinal structure. The in vitro model presented here provides a means of studying the regulation of this collagen production throughout intestinal organogenesis.