D.M. Foote, J.B. Muyskens, H.C. Dreyer

University of Oregon, Eugene, OR

PURPOSE: We have previously measured a 14% reduction in quadriceps volume 2 weeks after total knee arthroplasty TKA in the operative leg corresponding to a rate of loss of 1% per day. However, when TKA patients ingested 20 g of essential amino acids (EAA) twice daily for 7 days leading up to surgery and then for 2 weeks after TKA, atrophy rates were significantly less.In a recently completed follow up study using the same EAA supplementation, we obtained muscle biopsies at baseline and one week after surgery and performed transcriptomics analysis to uncover cellular pathways that were differentially expressed relative to Placebo control. Results showed prostaglandin to be a potential pathway that participates in attenuating atrophy post-TKA in patients on EAA. Ptger4 (EP4), a membrane bound receptor, achieves activation through the binding of its ligand, prostaglandin E2 (PGE2). This study aimed to determine the effect of PGE2 (10ng/ml, 100ng/ml, Veh (EtOH)) on the proliferative growth of cultured, early-passage, primary muscle cells obtained from our TKA patients. METHODS: Primary muscle cells were obtained via muscle biopsy of vastus lateralus from TKA patients participating in a clinical trial. Biopsies were explanted in culture and primary muscle cells purified via addition of a fibroblast inhibitor. Culture purity was determined using muscle and fibroblast cellular markers. Primary cells were plated in duplicate for each condition (Veh, 10ng, 100ng) and PGE2 or Veh added for 24 hours. Cell proliferation was measured via Ki67+and EdU incorporation. RESULTS: The 100ng-treated group had significantly greater Ki67+cells than Veh (25 +9 vs. 18 +5, p=0.023), and 10ng produced a trend for significance (24+12 vs. 18 +5, p=0.076). CONCLUSIONS: Our data suggest that PGE2 supplementation produces a dose-related increase in proliferation (24h) of aged human primary muscle cells in vitro.


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