Abstract ID#: 100464Structure-Osteoblastic-Activity Relationship on Phopsholipids Modified Surfaces

Objective: To overcome the problems associated with plasma-sprayed hydroxyapatite (HA) coating, a novel technology to biomimetically coat titanium (Ti) with calcium species has been developed. Various in-vivo calcium deposition processes are initiated by calcium phosphate complex of phospholipids (Ca-PL-PO4). This report presents the comparative potential of different phospholipids structural features towards mineralization and osteoblast response. Methods: Part-1: To investigate the effect of polar head group Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) were treated the same way as to convert them to calcium phosphate complex and were coated on solid surfaces. HEPM, an osteoblast precursor cell line, were cultured on these discs to study their differentiation into osteoblasts. The culture medium was removed and assayed for total protein production (TPP) and alkaline phosphatase specific activity (ALP) at 0, 7, and 14 days. Part-2: To investigate the effect of fatty acyl chains in glyceryl backbone part of the most active phospholipid, four synthetic PS analogs with varying fatty acyl chain length and unsaturation were converted to CaP complex, coated on Ti discs, and evaluated the same way for the differentiation, growth and biochemistry of HEPMs in culture as described in part-I. In all experiment, the relative uncoated surfaces were used as control. Results: Osteoblastic activity was evaluated by ALP. TPP indicated the cellular recognition of surface for adhesion. The best of both activities was exhibited by phopsphorylserine polar head group. Within PS analogs, the inclusion of unsaturation in fatty acyl chains at position-1 and -2 of glyceryl backbone enhanced both activities. Conclusions: The usefulness of Ca-PS-PO4 coated Ti surfaces in implantology is evident. Structural variations with unsaturated long-chain fatty-acyl group at positions-1 and -2 of glyceryl back-bone of PS exhibited best osteogenic activities. Supported by NIH fundings #R44DE13996 (NIDCR) and R43AR054287 (NIAMS) and by # DMI-0319490 (NSF).