Pulsed electromagnetic field (PEMF) transiently stimulates the rate of mineralization in a 3-dimensional ring culture model of osteogenesis

Pulsed Electromagnetic Frequencies (PEMF) have shown efficacy in bone repair and yet the optimum characteristics of this modality and its molecular mechanism remain unclear.  To determine the effects of timing of PEMF treatment we present a three-dimensional ring culture model of osteogenesis that demonstrates strong de novo generation of collagen and mineral matrix and exhibits stimulation by PEMF in multiple stages over 62 days of culture.  Mouse postnatal day 2 calvarial pre-osteoblasts were cast within and around Teflon rings by polymerization of fibrinogen and cultured suspended without contact with tissue culture plastic.  Ring constructs were exposed to PEMF for 4h/day for the entire culture (Daily), or just during Day1-Day10, Day11-Day 27, or Day28-Day63 and cultured without PEMF for the preceding or remaining days, and compared to no-PEMF controls. PEMF was conducted as HF Physio, 40.85 kHz frequency with a 67 ms burst period.  Osteogenesis was kinetically monitored by repeated...