Molecular characterisation of osteoblasts from bone obtained from people of Polynesian and European ancestry undergoing joint replacement surgery

Dorit Naot,Karen E Callon,Brya G Matthews,Anne Horne,Ian R Reid,Usha Bava,Jillian Cornish,Rocco P Pitto,Cluny Macpherson,Ally J Choi,Ryan Gao,Jarome Bentley,Gregory D Gamble

doi:10.1038/s41598-021-81731-5

Abstract

Population studies in Aotearoa New Zealand found higher bone mineral density and lower rate of hip fracture in people of Polynesian ancestry compared to Europeans. We hypothesised that differences in osteoblast proliferation and differentiation contribute to the differences in bone properties between the two groups. Osteoblasts were cultured from bone samples obtained from 30 people of Polynesian ancestry and 25 Europeans who had joint replacement surgeries for osteoarthritis. The fraction of cells in S-phase was determined by flow cytometry, and gene expression was analysed by microarray and real-time PCR. We found no differences in the fraction of osteoblasts in S-phase between the groups. Global gene expression analysis identified 79 differentially expressed genes (fold change > 2, FDR P < 0.1). Analysis of selected genes by real-time PCR found higher expression of COL1A1 and KRT34 in Polynesians, whereas BGLAP, DKK1, NOV, CDH13, EFHD1 and EFNB2 were higher in Europeans (P ≤ 0.01). Osteoblasts from European donors had higher levels of late differentiation markers and genes encoding proteins that inhibit the Wnt signalling pathway. This variability may contribute to the differences in bone properties between people of Polynesian and European ancestry that had been determined in previous studies.

Highlights

Population studies in Aotearoa New Zealand found higher bone mineral density and lower rate of hip fracture in people of Polynesian ancestry compared to Europeans
In order to test the hypothesis that increased osteoblast proliferation contributes to the favourable bone properties of people of Polynesian ancestry that had been described in the literature[6,7], the fraction of cells in different phases of the cell cycle were determined
This study characterised osteoblasts cultured from bone samples that were obtained from patients undergoing joint replacement surgeries for osteoarthritis, and compared between cells that originated from people who identified as Polynesians and those who identified as Europeans

Summary

Introduction

Population studies in Aotearoa New Zealand found higher bone mineral density and lower rate of hip fracture in people of Polynesian ancestry compared to Europeans. Osteoblasts from European donors had higher levels of late differentiation markers and genes encoding proteins that inhibit the Wnt signalling pathway This variability may contribute to the differences in bone properties between people of Polynesian and European ancestry that had been determined in previous studies. The NORA study found that after adjusting for multiple covariates, including weight, Asian women had similar BMD to auckland.ac.nz White women, but their fracture risk was considerably lower. Bone properties in different ethnic groups have been studied in Aotearoa New Zealand, a country with a large Polynesian population, comprised of Māori and Pacific peoples. Ethnic variations in the profile of gene expression in bone have not been investigated

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