Porous silk scaffolds for delivery of growth factors and stem cells to enhance bone regeneration.

Wenjie Zhang,Dongxia Ye,Xinquan Jiang,Ling Xu,Xiuli Zhang,Qianju Wu,David L Kaplan,Chao Zhu,Xiaochen Zhang,Abhay Pandit

doi:10.1371/journal.pone.0102371

Abstract

Stem cell-based tissue engineering shows promise for bone regeneration and requires artificial microenvironments to enhance the survival, proliferation and differentiation of the seeded cells. Silk fibroin, as a natural protein polymer, has unique properties for tissue regeneration. The present study aimed to evaluate the influence of porous silk scaffolds on rat bone marrow stem cells (BMSCs) by lenti-GFP tracking both in vitro and in vivo in cranial bone defects. The number of cells seeded within silk scaffolds in rat cranial bone defects increased from 2 days to 2 weeks after implantation, followed by a decrease at eight weeks. Importantly, the implanted cells survived for 8 weeks in vivo and some of the cells might differentiate into endothelial cells and osteoblasts induced by the presence of VEGF and BMP-2 in the scaffolds to promote angiogenesis and osteogenesis. The results demonstrate that porous silk scaffolds provide a suitable niche to maintain long survival and function of the implanted cells for bone regeneration.

Highlights

Tissue-engineered bone is a relatively new strategy to treat massive bone defects, instead of the use of autologous bone grafts which present drawbacks [1,2]
Fate of rat bone marrow stem cells (BMSCs) with silk scaffolds in vitro Rat BMSCs labeled with GFP were seeded in the porous silk scaffolds and incubated in DMEM in vitro
More cells were observed at 2 weeks and we concluded that the silk scaffold was favorable for promoting the survival and proliferation of rat BMSCs

Summary

Introduction

Tissue-engineered bone is a relatively new strategy to treat massive bone defects, instead of the use of autologous bone grafts which present drawbacks [1,2]. The long-term survival of seeded cells after transplantation along with biomaterial scaffolds is a prerequisite for the cells to promote tissue regeneration by directly participating in the process or by secreting key growth factors. For bone tissue engineering scaffolds, essential characteristics, such as a highly porous structure, mechanical properties, biocompatibility, slow degradation and suitable surface chemistry are key [13]. With all of these requirements taken into consideration, porous silk scaffolds offer very useful features to meet these needs as a carrier for stem cells in bone tissue engineering

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