Role of culture conditions on in vitrotransformation and cellular colonizationof biomimetic HA-Col scaffolds

摘要

We have recently developed new 3D hydroxyapatite/collagen (50/50 wt%) scaffolds using a biomimetic synthesisapproach. The first in vitro tests performed in static culture showed a limited cell colonization and survival inside thescaffolds. The current study evaluated in dynamic culture the scaffold changes and colonization by human immortalizedosteoprogenitor STRO-1A cells. The stability of our scaffolds in the different culture conditions (static, low flow, highflow) was validated by the maintenance of the pore diameter and interconnectivity over 21 d. The colonization and theviability of STRO-1A cells inside the scaffolds were further evaluated on histological sections. It was demonstrated thatonly the high flow-rate allowed cell survival after 7 d and a complete scaffold colonization. Moreover, the colonizationand viability were different in function of the scaffold position inside the perfusion container. The differentiation markers(alkaline phosphatase activity, type I procollagen and osteocalcin synthesis) of STRO-1A cells were analyzed in the culturemedium after 7, 14 and 21 d. The low flow-rate increased significantly the three markers compared with static conditions.In contrast, markers were reduced in high flow-rate compared with low flow-rate. To explain this surprising result, wehypothesized that the different molecules were actually adsorbed on the scaffold because of the closed circuit used inthe high flow-rate conditions. In summary, this study provides original results on the influence of flow rate but mostly ofthe circuit used (open/closed) on the structural modifications and cell colonization of collagen-HA scaffolds.