Biomedical subjects

Barry Bavister

Publications and source records attributed to Barry Bavister.

3 recordsLinked to original sources

PubMed2006

Differentiation-related changes in mitochondrial properties as indicators of stem cell competence.

Several methods may be used to assess stem cell competence, including the expression of cell surface markers and telomerase activity. We hypothesized that mitochondrial characteristics might be an additional and reliable way to verify stem cell competence. In a multipotent, adult monkey stromal stem cell line, previously shown to differentiate into adipocytes, chondrocytes, and osteocytes, we found that several mitochondrial properties change with increasing passage number in culture. Cells from the earliest passage (P11) versus those from a later passage (P17) are characterized by: (a) a much higher percentage of cells (85% vs. 18%) with a perinuclear arrangement of mitochondria; (b) a much lower percentage of cells (1% vs. 57%) with an aggregated mitochondrial arrangement, in which mitochondria appear to coalesce into large clumps; (c) a much lower percentage of cells with lipid droplets (1% vs. 36%), suggesting less differentiation into adipocytes; (d) a 5.6-fold lower ATP content per cell (0.45 vs. 2.51 pmoles ATP/cell; and (e) a 10-fold higher rate of oxygen consumption (37.8 vs. 3.8 nmoles O2/min/10(3) cells), indicating a higher metabolic activity. Collectively, these data indicate that the perinuclear arrangement of mitochondria, accompanied by a low ATP/cell content and a high rate of oxygen consumption, may be valid indicators of stem cell differentiation competence, while departures from this profile indicate that cells are differentiating or perhaps becoming senescent. These results represent the first characterization of mitochondrial properties reported for a primate stem cell line.

Adenosine Triphosphate↗

PubMed2004

Oxygen concentration and preimplantation development.

The recent article by Karagenc et al. once again shows that atmospheric oxygen is detrimental to embryo development in vitro. This study demonstrates that zygotes can readily develop into blastocysts under ambient oxygen, but in spite of their morphologically normal appearance, the viability of many of these embryos is compromised, with the most pronounced effect on ICM development. Numerous other studies have reached the same general conclusions, but in spite of the strong body of evidence derived from animal studies against using atmospheric oxygen, the entire human IVF community does not seem to have been convinced to abandon its use for embryo culture. This commentary argues for adoption of low oxygen concentrations as the standard for human embryo culture, at least for blastocyst production.

Animals↗

PubMed2004

The role of animal studies in supporting human assisted reproductive technology.

Although average success rates of human IVF have increased progressively during the past two decades, the efficiency of this technique, based on each embryo produced or transferred, is still low. High success rates are usually achieved by transferring several embryos to the patient, which is often associated with multiple pregnancies. The quality of in vitro produced embryos is a major area that needs attention. Because there is no in vivo database for human embryos, the properties of normal embryos are not known, and so it is difficult to know how to improve quality and viability. In addition, selection of the most viable embryos for transfer is a rather subjective process. The origins of human assisted reproductive technology (ART) are based on animal ART; however, the two areas of research (animal and human ART) appear to have become disconnected. Re-examination of progress in animal ART could help improve human embryo quality and thereby assist efforts to sustain high pregnancy rates with only one or two embryos transferred. Some key areas in which animal ART can help guide progress in human ART are discussed.

Animals↗