Cell Sources for Bone Tissue Engineering: Insights from Basic Science

Abstract

One of the goals of bone tissue engineering is to design delivery methods for skeletal stem/progenitor cells to repair or replace bone. Although the materials used to retain cells play a central role in the quality of the constructs, the source of cells is key for bone regeneration. Bone marrow is the most common cell source, but other tissues are now being explored, such as the periosteum, fat, muscle, cord blood, and embryonic or induced pluripotent stem cells. The therapeutic effect of exogenous stem/progenitor cells is accepted, yet their contribution to bone repair is not well defined. The in vitro osteo- and/or chondrogenic potential of these skeletal progenitors do not necessarily predict their differentiation potential in vivo and their function may be affected by their ability to home correctly to bone. This review provides an overview of animal models used to test the efficacy of cell-based approaches. We examine the mechanisms of endogenous cell recruitment during bone repair and compare the role of local versus systemic cell recruitment. We discuss how the normal repair process can help define efficacious cell sources for bone tissue engineering and improve their methods of delivery.

Mesenchymal Stem Cells in Bone Regeneration

“…The comparative quality and character, as well as the differentiation potential of MSCs from each of these sources varies and is still debated. 6 MSCs derived from bone marrow. The first identified source of a cell referred to as an MSC was the bone marrow (BM-MSC), and bone marrow remains a common source of cells.…”

“…9 Bone marrow can be readily accessed in comparatively plentiful quantities for use in expansion and therapeutics, which is one of the reasons that its use is very common in orthopedic surgery. 6 Particularly, it is likely that orthopedic surgeons are comfortable with the concept of using marrow-derived MSCs because cancellous bone is frequently used as autograft material in bone regeneration.…”

“…It is therefore plentiful, but can be difficult to harvest due to the cambrium layer being strongly attached to the bone surface. It is generally considered a more difficult tissue to harvest compared to bone marrow, 6 but can be readily accessed in certain surgical procedures. Due to its large in vivo contribution to production of new osteoblasts and chondrocytes locally, this tissue has a lot of promise as a source of MSCs for therapeutics.…”

“…2). Although MSCs from fat and muscle can differentiate into osteoblasts and chondrocytes in vitro, they have not been demonstrated as contributing to bone repair in vivo, 6 although some controversy exists as to whether muscle may also contribute MSCs to repair.…”

Determining the Role of Sost and Sostdc1 During Fracture Healing

“…Optimal fracture repair requires contribution from surrounding tissues, yet we know very little about the interactions between bone, muscle, vasculature, and the periosteum [173][174][175]. In particular the periosteum, a thin tissue that covers the outer cortical bone surface, contains a reservoir of progenitor cells that contribute to bone repair; further, periosteal grafts and alpha-smooth muscle actin (α-SMA)-positive cells integrate into the callus after fracture [105,175].…”