Engaging Stem Cells for Customized Tendon Regeneration

Abstract

The need for a consistent therapeutic approach to tendon injury repair is long overdue. Patients with tendon microtears or full ruptures are eligible for a wide range of invasive and non invasive interventions, often subjectively decided by the physician. Surgery produces the best outcomes, and while studies have been conducted to optimize graft constructs and to track outcomes, the data from these studies have been inconclusive on the whole. What has been established is a clear understanding of healthy tendon architecture and the inherent process of healing. With this knowledge, tissue regeneration efforts have achieved immense progress in scaffold design, cell line selection, and, more recently, the appropriate use of cytokines and growth factors. This paper evaluates the plasticity of bone-marrow-derived stem cells and the elasticity of recently developed biomaterials towards tendon regeneration efforts. Mesenchymal stem cells (MSCs), hematopoietic progenitor cells, and poly(1,8-octanediol co-citrate) scaffolds (POC) are discussed in the context of established grafting strategies. With POC scaffolds to cradle the growth of MSCs and hematopoietic progenitor cells, developing a fibroelastic network guided by cytokines and growth factors may contribute towards consistent graft constructs, enhanced functionality, and better patient outcomes.

Semitendinosus tendon regeneration after anterior cruciate ligament reconstruction: can we use it twice?

“…It is expected that injured vascular capillary networks in the surrounding connective tissue sprout capillary buds along the tubular space of missing tendon. PDGF initiates and guides fibroblast activation, proliferation, and migration [26].…”

“…MSCs differentiate into tenocytes (elongated fibroblasts) which are important in collagen synthesis within the extracellular matrix. MSCs produce human foetal tendonspecific matrix components and differentiation factors, which then activate the endogenous regeneration process in tendons [26].…”

Therapeutic Strategies for Tendon Healing Based on Novel Biomaterials, Factors and Cells

“…They are processed to remove noncollagen components while retaining the natural collagen structure (predominantly collagen I fibers) and mechanical properties [15]. Materials that have been approved by the Food and Drug Administration (FDA) include Restore™ and CuffPatch (both from SIS), OrthADAPT™ (equine pericardium), Zimmer collagen repair patch and Permacol (both porcine acellular dermal matrix), Bio-BlanketW, TissueMend (bovine dermis and bovine dermal ECM) and GraftJacket (human acellular dermal matrix) [16]. The major drawback of these commercial biological scaffolds is that they have significantly less mechanical properties than normal tendons [17].…”

“…Nondegradable synthetic polymers with FDA approval for tendon repair include polyethylene terephthalate, polypropylene and poly(tetrafluoroethylene) [16]. Several biodegradable synthetic polymers have also obtained FDA approval.…”

“…Several biodegradable synthetic polymers have also obtained FDA approval. These include polylactic and polyglycolic acid, polycaprolactone and polydioxanone [16]. Several polymers (both nondegradable and degradable) may support growth factor release and therefore offer even greater flexibility.…”