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The increase of adipose tissue mass associated with obesity is due in part to an increase in the number of adipocytes. This hyperplasia results from recruitment of pluripotent stem cells present in the vascular stroma of adipose tissue. A model cell culture system has been developed that recapitulates this process both ex vivo and in vivo. After treatment of pluripotent C3H10T1/2 stem cells with bone morphogenic protein 4 (BMP4) during proliferation followed by differentiation inducers at growth arrest, the cells synchronously enter S phase and undergo mitotic clonal expansion, a hallmark of preadipocyte differentiation. Upon exiting the cell cycle, these cells express adipocyte markers and acquire adipocyte characteristics at high frequency. C3H10T1/2 cells treated with BMP4 in cell culture and implanted s.c. into athymic mice develop into tissue indistinguishable from adipose tissue in normal fat depots. We interpret the findings as evidence that BMP4 is capable of triggering commitment of pluripotent C3H10T1/2 stem cells to the adipocyte lineage. adipose tissue | differentiation | bone morphogenic protein 4 | mitotic clonal expansion | development

Research has been conducted on the null mouse gastric mucosa. Results indicate that this mucosa exhibits hyperplasias caused by stimulated proliferation and suppressed apoptosis in the cells.

Transcription factors expressed in the cells of the developing respiratory tract affect the transcription of mRNAs of genes, and control development and pattern formation in the lungs. An increase in the activity of the retinoic acid receptor (RAR) -beta-4 causes hyperplasia in the lung epithelium. Null mutations of the N-myc protooncogene cause lethal defects in the lung. Other transcription factors such as the products of the Hox, Hlx and Hex genes, steroid and thyroid hormone receptors are also expressed in the lungs, and affect lung development and pattern formation.

Focal nodular hyperplasia of the liver is a rare condition characterized by excessive cell growth (hyperplasia), that occurs most often in women of child-bearing age. The condition is often asymptomatic and discovered incidentally during surgery for another condition; sometimes pain or a palpable mass indicate the presence of scar tissue in the liver. Little is known about the natural history of the condition or the optimal treatment strategy for this condition. To further categorize this disorder, the records of 22 patients (19 women) with focal nodular hyperplasia of the liver were reviewed. Fourteen of the patients had symptoms, such as pain or swelling, which led to diagnosis; the remaining patients were symptom-free. Of the 14 adult women in the group, 12 had taken oral contraceptives. Twelve patients underwent surgical removal of the hyperplastic region; four patients underwent hepatic artery ligation. Five patients were given no treatment (conservative treatment); two of these asymptomatic patients remained symptom-free, whereas one patient who was taking oral contraceptives became symptom-free when she stopped taking these pills. Hence, this relatively benign condition requires a flexible approach to treatment. In some cases, conservative treatment will suffice; the majority of cases, requiring more active management, respond favorably to surgical removal of the hyperplastic focus. In a minority of cases, the symptoms may be induced by oral contraceptive use but these symptoms improve after discontinuation. (Consumer Summary produced by Reliance Medical Information, Inc.)

A study demonstrates that B lymphocyte-induced maturation protein 1 (Blimp1) appears to govern cellular input into the sebaceous gland (SG) since its loss leads to elevated c-myc expression, augmented cell proliferation, and SG hyperplasia. BrdU labeling experiments demonstrate that the SG defects associated with loss of Blimp 1 lead to enhanced bulge stem cell activity, suggesting that when normal SG homeostasis is perturbed, multipotent stem cells in the bulge can be mobilized to correct the imbalance.