Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA.
Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA; BioFrontiers Institute, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA; Material Science and Engineering Program, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA.
Acta Biomater. 2018 Apr 15;71:37-48. doi: 10.1016/j.actbio.2018.02.026. Epub 2018 Mar 2.
Poly(ethylene glycol) PEG-based hydrogels are promising for cell encapsulation and tissue engineering, but are known to elicit a foreign body response (FBR) in vivo. The goal of this study was to investigate the impact of the FBR, and specifically the presence of inflammatory macrophages, on encapsulated cells and their ability to synthesize new extracellular matrix. This study employed an in vitro co-culture system with murine macrophages and MC3T3-E1 pre-osteoblasts encapsulated in a bone-mimetic hydrogel, which were cultured in transwell inserts, and exposed to an inflammatory stimulant, lipopolysaccharide (LPS). The co-culture was compared to mono-cultures of the cell-laden hydrogels alone and with LPS over 28 days. Two macrophage cell sources, RAW 264.7 and primary derived, were investigated. The presence of LPS-stimulated primary macrophages led to significant changes in the cell-laden hydrogel by a 5.3-fold increase in percent apoptotic osteoblasts at day 28, 4.2-fold decrease in alkaline phosphatase activity at day 10, and 7-fold decrease in collagen deposition. The presence of LPS-stimulated RAW macrophages led to significant changes in the cell-laden hydrogel by 5-fold decrease in alkaline phosphatase activity at day 10 and 4-fold decrease in collagen deposition. Mineralization, as measured by von Kossa stain or quantified by calcium content, was not sensitive to macrophages or LPS. Elevated interleukin-6 and tumor necrosis factor-α secretion were detected in mono-cultures with LPS and co-cultures. Overall, primary macrophages had a more severe inhibitory effect on osteoblast differentiation than the macrophage cell line, with greater apoptosis and collagen I reduction. In summary, this study highlights the detrimental effects of macrophages on encapsulated cells for bone tissue engineering.
Poly(ethylene glycol) (PEG)-based hydrogels are promising for cell encapsulation and tissue engineering, but are known to elicit a foreign body response (FBR) in vivo. The impact of the FBR on encapsulated cells and their ability to synthesize tissue has not been well studied. This study utilizes thiol-ene click chemistry to create a biomimetic, enzymatically degradable hydrogel system with which to encapsulate MC3T3-E1 pre-osteoblasts. The osteogenic capabilities and differentiation of these cellswerestudied in co-culture with macrophages, known drivers of the FBR.This study demonstrates that macrophages reduce osteogenic capabilities of encapsulated cellsin vitroand suggestthat the FBR should be considered for in vivo tissue engineering.
聚乙二醇（PEG）基水凝胶在细胞包封和组织工程中很有前景，但已知在体内会引发异物反应（FBR）。本研究的目的是研究 FBR 的影响，特别是炎症性巨噬细胞的存在对包封细胞及其合成新细胞外基质的能力的影响。本研究采用体外共培养系统，将鼠巨噬细胞和 MC3T3-E1 成骨前体细胞包封在仿生水凝胶中，这些细胞在 Transwell 插入物中培养，并暴露于炎症刺激物脂多糖（LPS）。将共培养与单独的负载细胞的水凝胶和 LPS 共培养进行了比较，培养时间为 28 天。研究了两种巨噬细胞来源，RAW 264.7 和原代衍生的巨噬细胞。在第 28 天，LPS 刺激的原代巨噬细胞使负载细胞的水凝胶中的成骨细胞凋亡率增加了 5.3 倍，碱性磷酸酶活性降低了 4.2 倍，胶原沉积减少了 7 倍。LPS 刺激的 RAW 巨噬细胞使负载细胞的水凝胶中的碱性磷酸酶活性降低了 5 倍，胶原沉积减少了 4 倍。通过 von Kossa 染色或钙含量定量来测量的矿化作用对巨噬细胞或 LPS 不敏感。在 LPS 存在的单核培养物和共培养物中检测到白细胞介素-6 和肿瘤坏死因子-α的分泌升高。总体而言，原代巨噬细胞对成骨细胞分化的抑制作用比巨噬细胞系更严重，细胞凋亡和 I 型胶原减少更多。总之，本研究强调了巨噬细胞对骨组织工程中包封细胞的有害影响。
