Bone regeneration: the challenge and the key to success.

Objectives: Bone tissue repair is one of the major concerns of regenerative medicine. In general, bone is a dynamic tissue that can remodel and repair itself, but bone repair is documented to be insufficient in some cases when large bone is damaged. Although bone grafts and substitutes are used in these cases, they still do not provide a complete solution for bone lost problem. Hence, to solve this problem, bone tissue engineering techniques have emerged by combining biology, biomaterials scaffolds and mechanics. The aim of these techniques is developing bone tissue with similar mechanical strength, microstructure and function to naturally occurring bone, through fabricating a porous 3D scaffold that provide a suitable environment for cell proliferation, growth and differentiation. Yet, in order to improve the survival and function of the engineered tissue, it's crucial to establish of efficient vascularization into it. Vascularization is essential for nutrients supplement to the tissue and metabolism byproducts clearance from it.
Methods: We present a novel bio-engineered scaffold with a built-in vascular system, made of electrospun PCL tubes surrounded with a bulk of osteoconductive Pro-Osteon ceramics and PCL fibers
Results: Our results demonstrate that this porous engineered 3D scaffold has most of the features required for effective bone-tissue engineered construct. It is porous and permeable, biocompatible to cells and host, non-toxic and non-inflammatory and also osteoconductive. Therefore, it could serve as temporary extracellular matrix (ECM) for the seeded mesenchymal stem cells (MSCs) where they could integrate, adhere, proliferate and differentiate into several tissues, especially bone tissue
Conclusions: Our 3D electrospun scaffold could function as perfusion bioreactors that provide the tissue with immediate supply of nutrients and oxygen in order to improve tissue homogenous development in vitro and keep its viability after implanting in vivo.