Study On UHMWPE Carrying Estradiol

The wear debris-induced osteolysis was considered as the main reason for the aseptic loosening after total hip arthroplasty. And it has been well reported that the UHMWPE wear particles was the major concern for the osteolysis.Further consideration has now been given to the drug treatment of the osteolysis by topical administration. It has not been found that ultra-high molecular weight polyethylene (UHMWPE) was used as the drug carrier to prevent the particle-induced osteolysis. Therefore, 17β-estradiol (E2), which had the potential application on osteolysis treatment and the high melting point, was added into UHMWPE powder to produce UHMWPE-E2 composites through hot press processing. It was expected that E2 in the UHMWPE-E2 acetabular cup could be released with the inevitable UHMWPE wear particles to prevent the artificial joint loosening finally.The functional group, water contact angle, crystallinity, mechanical properties and wear performance of UHMWPE-E2 was characterized compared to the control UHMWPE in the present study. And the in vitro drug release for the UHMWPE-E2 wear debris was investigated. The UHMWPE-E2 wear debris was co-cultured with osteoblasts and macrophages to investigate their biological reaction to the wear debris including the cell proliferation, differentiation and the expression of osteolysis factors.The Thermal Analysis (TA) and Fourier Transform Infrared Spectroscopy (FTIR) results demonstrated that the hot press processing would not alter the function group of E2 in this study. There was no significant difference in hydrophobicity and crystallinity between UHMWPE-E2 and UHMWPE. The UHMWPE-E2 showed satisfying mechanical properties, including ultimate tensile strength (47.2±3.6 MPa), yield strength (25.0±0.6 MPa) and elongation at break (320±25.5 %), which satisfied the demanding of the ASTM F 648-04. The friction coefficients and worn scars were similar between the UHMWPE-E2 and the control UHMWPE. The wear mechanism of UHMWPE-E2 and UHMWPE both were abrasive wear under dry friction.The results of the in vitro drug release showed that there were three stages during the release process including initial sudden release, the following celerity release and final steady release. And the drug release amount satisfied the demanding of clinic during the final steady release.The results of the cell culture indicated that the UHMWPE-E2 wear debris could promote the proliferation and the ALP expression of osteoblasts in some certain dosages. Most important of all, the UHMWPE-E2 wear debris could inhibit the expression of IL-6 at all dosages in the present study, which indicated that the estradiol in UHMWPE-E2 might play a role in the treatment of the osteolysis in artificial hip joint. There was no significant difference in the promotion of the macrophages proliferation between the UHMWPE-E2 and UHMWPE wear debris and they all stimulated the phagocytosis of the macrophages.The present study indicated that the UHMWPE-E2 possessed the approving mechanical properties and wear performance compared to the control UHMWPE, which might be used the potential implanted drug carrier to prevent the particle-induced osteolysis in joint replacements. Moreover the estradiol in the UHMWPE-E2 wear debris could directly promote the proliferation of osteblasts and inhibit the secretion of the osteolysis factor IL-6. Therefore it might prevent the osteolysis and prolong the lifetime of the artificial hip joint finally.