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Biomedical subjects

A Pocock

Publications and source records attributed to A Pocock.

3 recordsLinked to original sources
PubMed1998

Proliferation and collagen synthesis of human anterior cruciate ligament cells in vitro: effects of ascorbate-2-phosphate, dexamethasone and oxygen tension.

Clinical and experimental studies demonstrate that injured anterior cruciate ligaments (ACL) do not usually heal and that autografts used to repair the ACL rapidly weaken in the early period and take a long time to regain strength. The aim of this study was to develop an in vitro culture system in which environmental and biochemical factors influencing the proliferation and matrix synthesis of cells derived from human anterior cruciate ligaments can be studied. Primary cultures of human ACL cells were obtained by outgrowth from explants of normal ACL obtained at knee replacement for osteoarthritis in Dulbecco's minimum essential medium (DMEM). The effects of the additives 100 microm L-ascorbic acid-2-phosphate (Asc-2-P) and 10 n m dexamethasone (dex) on proliferation and collagen synthesis were assessed after 4, 8 and 12 days in culture. Ligament cells were grown at 0, 5, 10 and 21%p O(2)in the presence of 100 microm asc-2-P and 10 n m dex. DNA content was assessed using the Hoechst dye method and collagen synthesis by the incorporation of 5 mCi/ml [(3)H]proline after 3, 6 and 12 days in culture. At 21%p O(2), the presence of asc-2-P and dex induced significantly greater (P< 0.01, ANOVA) cell proliferation than with either additives alone. Greatest percentage collagen to total protein synthesis was observed when cells were grown in the presence of asc-2-P only. Least proliferation and percentage collagen to total protein synthesis was seen when both additives were omitted. Greatest cell proliferation was seen when cells were grown in 10%p O(2)and 5%p O(2)was associated with increased collagen synthesis. These results suggest that it is possible to study the effects of environmental and biochemical factors on human ACL healing in vitro. Our data suggest oxygen can influence certain biosynthetic activities of ACL cells. Low oxygen tensions lead to an increase in collagen production by ACL cells. However early responses to injury require extensive cell proliferation which may be activated at higher p O(2). Variation of p O(2)in ligaments during healing may therefore be an important modulator of successful repair.

Anterior Cruciate Ligament↗
PubMed1998

Primary human osteoblast proliferation and prostaglandin E2 release in response to mechanical strain in vitro.

The application of mechanical loads to bone cells in vitro has been found to generate variable responses, which may in part be due to the source of the cell used and the characteristics of the strain applied. The aim of this study was to establish a system for applying well-defined physiological levels of mechanical strain to a well-defined population of human osteoblast-like cells. Human bone-derived cells obtained from the greater trochanter of the femur during total hip arthroplasty for osteoarthritis were cultured in the presence of 10 nmol/L dexamethasone and 100 mumol/L L-ascorbate-2-phosphate. Replicates of cells from each patient were loaded on separate occasions using controlled cyclical strains of 4000 microstrain (mu epsilon) or less. Strain gauges recorded reliable, reproducible strains between 1000 and 6000 mu epsilon. To establish reproducibility, sequential explant cultures derived from two patients were studied. A consistent increase (p < 0.05) in proliferation between replicates and explants derived from one patient subjected to 1600 mu epsilon on separate occasions was observed. Cells derived from sequential explants of the second patient showed no consistent increase in proliferation between replicates and explants. Three of six patients showed a significant increase (p < 0.05) in PGE2 production after 5 h in response to stretch (4000 mu epsilon) in all replicates on separate occasions, whereas, in the other three populations of cells, no increase in PGE2 was measured in any of the replicates. These results show that the application of highly controlled strains causes a significant effect on human bone cells, but only in a proportion of subjects. The response is consistent between sequential explants derived from the same patient. The implications of this study are that human osteoblast-like cells do respond to physiological strain in vitro, although some cells are more strain sensitive than others.

Anti-Inflammatory Agents↗