Current Stem Cell Research & Therapy - Volume 11, Issue 6, 2016

This review surveys the use of pluripotent and multipotent stem cells in skeletal tissue engineering. Specific emphasis is focused on evaluating the function and activities of these cells in the context of development in vivo, and how technologies and methods of stem cell-based tissue engineering for stem cells must draw inspiration from developmental biology. Information on the embryonic origin and in vivo differentiation of skeletal tissues is first reviewed, to shed light on the persistence and activities of adult stem cells that remain in skeletal tissues after embryogenesis. Next, the development and differentiation of pluripotent stem cells is discussed, and some of their advantages and disadvantages in the context of tissue engineering are presented. The final section highlights current use of multipotent adult mesenchymal stem cells, reviewing their origin, differentiation capacity, and potential applications to tissue engineering.

Advancements in biomaterials and stem cell technology have lead current medical technology to tissue engineering and regenerative medicine. Human engineered cartilage, bone, fascia, tendon, nerve and skin tissues have been used for the treatment of tissue injuries and degenerative diseases in combination with embryonic, fetal or adult stem and progenitor cells. Mesenchymal stem cells are one of the most extensively studied adult stem cell population and are widely utilized in cell therapies. Regeneration and 3-dimensional reconstruction of specialized connective tissues by combining differently originated micro and nanoscaled, natural or synthetic scaffolds with stem or progenitor cells are highly expected to guarantee patients to maintain acceptable life quality. In this review we discuss the important issues in biomaterial and stem cell interactions based on histological biocompatibility, updating recent basic research in this field and addressing possible future perspectives.

Orthopedic disorders and trauma usually result in bone loss. Bone grafts are widely used to replace this tissue. Bone grafts excluding autografts unfortunately have disadvantages like evoking immune response, contamination and rejection. Autografts are of limited sources and optimum biomaterials that can replace bone have been searched for several decades. Bioceramics, which have the similar inorganic structure of natural bone, are widely used to regenerate bone or coat metallic implants. As people continuously look for a higher life quality, there are developments in technology almost everyday to meet their expectations. Nanotechnology is one of such technologies and it attracts everyone’s attention in biomaterial science. Nano scale biomaterials have many advantages like larger surface area and higher biocompatibility and these properties make them more preferable than micro scale. Also, stem cells are used for bone regeneration besides nano-bioceramics due to their differentiation characteristics. This review covers current research on nano-bioceramics and mesenchymal stem cells and their role in bone regeneration.

Long bone fractures in diabetics are slower to heal, have an increased risk of developing non-union and demonstrate greater potential of infection and perioperative complications compared to non-diabetics. The causative aberrant bone mineral density and insufficient bone microstructure of diabetic patients are thought to result from altered osteoblast and osteocyte function, increased bone marrow adiposity, decreased progenitor osteo- and chondral differentiation potential and increased pro-inflammatory cytokine circulation. It is therefore reasonable to hypothesize that the root cause of faulty diabetic bone homeostasis and fracture repair is a reduced population of bone marrow progenitor cells and/or their decreased osteochondral capacity complicated by their repressed neo-vascular potential. The potential of transplanted mesenchymal stem cells with a scaffold to support callus formation through the creation of de novo bone in hyperglycemia has been reported. However, there are minimal supporting pre-clinical and clinical investigations confirming these findings. Clinical trials have instead examined mesenchymal stem cell transplantation to slow disease progression, support β-cell viability and function and restore glucose homeostasis while the direct application of allogenic non-diabetic mesenchymal stem cells at the site of orthopaedic injury remains un-investigated. Here, the literature supporting the application of mesenchymal stem cells in diabetic fracture repair is reviewed including the process of dysfunctional diabetic fracture healing, osteoblast dysregulation and the effect of the hyperglycaemic environment on progenitor cell number and performance with a view to translating the preclinical knowledge base to the administration of mesenchymal stem cells in diabetic fracture repair.

Intervertebral disc degeneration is a common spinal disorder and may manifest with low back pain or sciatica. The degeneration is characterized by the loss of extracellular matrix integrity and dehydration in the nucleus pulposus. This compromises the viscoelastic property and compressive strength of the disc and therefore the capacity to withstand axial load, eventually causing the disc to collapse or leading to disc bulging or herniation due to abnormal strains on the surrounding annulus. Mesenchymal stem/stromal cells (MSCs) are attractive cell sources for engineering or repair of the disc tissues with respect to their ease of availability and capacity to expand in vitro. Moreover, recent investigations have proposed a potential of MSCs to differentiate into disc-like cells. This review discusses the approaches and concerns for engineering intervertebral disc through manipulating MSCs, with a highlight on the relevance of disc progenitor discovery. Ultimately, stem cell-based engineering of intervertebral disc may facilitate the preservation of motion segment function and address degenerative disc disease in future without spinal fusion.

Endochondral ossification is under the regulation of endocrine, paracrine and otocrine factors including transforming growth factor-β superfamily members, fibroblast growth factors, retinoids, products of hedgehog gene, parathyroid hormone-related peptide, molecules involved in cell adhesion, and extracellular matrix components. Natriuretic peptide receptor-B, and its ligand C-type natriuretic peptide have also been implicated in the regulation of limb bone development. Results of recent studies are promising in terms of systemic elevation of C-type natriuretic peptide level inducing growth. In addition, same strategy also overcomes the dwarf phenotype of achondroplasia, the most frequently seen skeletal dysplasia in human, in a mouse model. Based on this literature and a series of recent experiments discussed here, this perspective underlines the abundant C-type natriuretic peptide expression in trabecular bone derived mesenchymal stem cells of human, chicken, and rat origin, and proposes the potential use of mesenchymal stem cells as a part of growth inducing treatment strategy in osteochondrodisyplasias in the future.

Stem cells are classified by their tissue source. Embryonic stem cells that are derived from the inner cell mass of blastocyst stage embryos are highly proliferative in their undifferentiated state. A multipotent type of mesenchymal stem cells is isolated from various types of tissues such as bone marrow, fat tissue etc. The dynamics of embryonic and adult stem cell cycles are profoundly dissimilar from the culture of stem cells. After improving the culture conditions and differentiation potentials, differentiated stem cells are the first cells to be preferred in modern regenerative medicine and tissue engineering. This review article focuses on the cell-based therapy of orthopedic problems. We explore the challenges associated with bone repair and regeneration using embryonic or mesenchymal stem cells that are in undifferentiated or/and differentiated condition. This paper also discusses optimizing the best cell type, differentiation condition and using them on bone tissue engineering for future investigations.