Environmental Optimization Enables Maintenance of Quiescent Hematopoietic Stem Cells Ex Vivo

Hematopoietic stem cells (HSCs) maintain lifelong hematopoiesis by remaining quiescent in the bone marrow niche. Recapitulation of a quiescent state in culture has not been achieved, as cells rapidly proliferate and differentiate in vitro. After exhaustive analysis of different environmental factor combinations and concentrations as a way to mimic physiological conditions, we were able to maintain engraftable quiescent HSCs for 1 month in culture under very low cytokine concentrations, hypoxia, and very high fatty acid levels. Exogenous fatty acids were required likely due to suppression of intrinsic fatty acid synthesis by hypoxia and low cytokine conditions. By contrast, high cytokine concentrations or normoxia induced HSC proliferation and differentiation. Our culture system provides a means to evaluate properties of steady-state HSCs and test effects of defined factors in vitro under near-physiological conditions.

Early-onset facioscapulohumeral muscular dystrophy: two case reports

This report concerns two patients with facioscapulohumeral muscular dystrophy (FSHD) whose facial weakness began in infancy. In both patients, biopsied muscle histology showed mild myogenic changes accompanied by some regenerating and some small angular fibers, while endomysial inflammatory cellular infiltration was observed in Patient 1. The finding that our very young patients had muscle histopathological findings compatible with classical FSHD supports the previously expressed view that muscle histopathology is not related to either age or duration of the disease. Although Patient 2 was a sporadic case, both patients had the abnormal EcoRI DNA fragment detected by Southern blot analysis with probes p13E-11 and pFR-1, a finding compatible with FSHD. This indicates that gene analysis of sporadic cases must be as significant as that of familial cases. This report on patients with very early-onset and with common muscle histopathological and molecular genetic findings should contribute to widening the clinical spectrum of FSHD.

Osteonecrosis after renal transplantation in children

From January 1975 to December 1990, 141 renal transplants were performed in 129 children. There were 72 boys and 57 girls, aged two to 17 years. Osteonecrosis occurred in seven patients, in the following sites: the femoral head in four children, including two bilateral cases; and the femoral condyle in three children, with two bilateral cases. The mean period from transplantation to the diagnosis of osteonecrosis was 18 months. The osteonecrosis group was compared to the control group and no statistically significant differences were found except in the serum cholesterol levels. The corticosteroid dosage in particular, showed no correlation with the occurrence of osteonecrosis.

Complications of Pemberton's pericapsular osteotomy. A report of two cases

Pemberton's pericapsular osteotomy has been performed since 1970 at the authors' institution on 56 hips in 49 patients. Two complications, obturator dislocation and osteonecrosis of the femoral head, occurred. A ten-year-old girl had an obturator dislocation that was recognized six weeks postoperatively. This dislocation probably occurred because the reduction of the acetabular dysplasia and the varus osteotomy were excessive in degree. Osteonecrosis of the femoral head was recognized in a 13-year-old girl six weeks postoperatively. This complication probably occurred because too much pressure was imposed on the femoral head, which had been dislocated for a long time and whose circumstances changed suddenly.