报告题目：OPTIMISING SURFACE CHARGE ON HYDROXYAPETITE COATINGS TO PROMOTE MESENCHYMAL STEM CELL DEVELOPMENT

报告时间：2017年5月18日（周四） 13：30

报告地点：18新利体育 南校区1号楼3楼骨科研究所317学术报告厅
报告人：David R Haynes教授（澳大利亚阿德莱德大学）

摘要：

Successful osteointegration of orthopaedic implants after surgery remains a significant issue particularly in our aging population. Hence it is important to develop materials that can provide the ideal natural environment for bone cells to develop. Hydroxyapatite (HA) as a coating on metallic implants has been successfully used clinically. Recent studies have suggested that a negative surface charge benefited implant fixation. Surface charge may also promote greater bone cell activity and the formation of more bone. This work studies the effects of negative surface charge on human mesenchymal stem cells (MSC). We hypothesised that surfaces with increased negative charge would enhance MSC growth and development into bone forming cells.

We maximized the surface charge in two ways. Firstly, the coatings were sprayed onto pre-heated metal to orient the crystals. Secondly, vacant OH sites are refilled, by placing the coating in water vapour, and then the OH- ions are oriented in an electric field. Both crystal orientation and OH ion orientation achieves the maximum charge possible. MSC were isolated from 4 human bone marrow aspirates from the posterior iliac crest of adults (20-35 years old). 3 surfaces were tested, high negative charge, low negative charge and glass coverslip controls. MSCs were seeded on HA and cultured in osteogenic induction media (STEMCELL Technol.) for 14 days. Replicate culture samples were isolated for Real Time PCR analysis.

Confocal microscopy was used to determine cell numbers by counting the blue staining (DAPI) nuclei and cell morphology assessed by the red staining (phalloidin) of the actin filaments. There was no marked difference between the surfaces. mRNA expression was assessed for MSC grown on 3 substrates. Expression of markers of proliferation (P16), “stemness” (OCT4 and bone forming phenotype (RUNX2) were assessed after 14 days. Results from the negatively charged HA did not show a change in the proliferation (p<0.05), but indicated a significantly higher level of “stemness” and bone forming cell phenotype compared to uncharged HA.

This data supports our hypothesis that surfaces with increased negative charge would enhance MSC growth and development into bone forming cells. Further investigations are required to determine protein factors pivotal to MSC growth and bone forming cell development. 

报告人简介：

Professor David R Haynes is Deputy Head of the Adelaide Medical School, University of Adelaide. He has published over 120 publications in respected peer reviewed journals. Over the past two decades he has developed a respected international reputation in the fields of bone pathologies, biomaterials and inflammation. Over the past decade he has been President and Secretary of the Australian and New Zealand Society of Orthopaedic Research (www.ANZORS.org.au). In these roles he has help organise more than 5 national and 3 international meetings. Associate Professor Haynes has been chief investigator on more than 17 successful major national and international grants (NH&MRC, European Union Framework 7 and ARC) grants since the early 1990’s as well as several commercially funded studies on pharmacological regulation of inflammatory cytokines, pathogenic bone loss and implant loosening. He also makes a significant contribution to the training of medical students (MBBS), Dental, Health Science and Nursing students in the Faculty of Health Sciences.