Preparation and in vitro/in vivo evaluations of dimpled poly(l-lactic acid) fibers mixed/coated with hydroxyapatite nanocrystals

Preclinical in vivo Performance of Novel Biodegradable, Electrospun Poly(lactic acid) and Poly(lactic-co-glycolic acid) Nanocomposites: A Review

Bone substitute materials have witnessed tremendous development over the past decades and autogenous bone may still be considered the gold standard for many clinicians and clinical approaches in order to rebuild and restore bone defects. However, a plethora of novel xenogenic and synthetic bone substitute materials have been introduced in recent years in the field of bone regeneration. As the development of bone is actually a calcification process within a collagen fiber arrangement, the use of scaffolds in the formation of fibers may offer some advantages, along with additional handling characteristics. This review focuses on material characteristics and degradation behavior of electrospun biodegradable polyester scaffolds. Furthermore, we concentrated on the preclinical in vivo performance with regard to bone regeneration in preclinical studies. The major findings are as follows: Scaffold composition and architecture determine its biological behavior and degradation characteristics; The incorporation of inorganic substances and/or organic substances within composite scaffolds enhances new bone formation; L-poly(lactic acid) and poly(lactic-co-glycolic acid) composite scaffolds, especially when combined with basic substances like hydroxyapatite, tricalcium phosphate or demineralized bone powder, seem not to induce inflammatory tissue reactions in vivo.

Effects of hydroxyapatite-containing composite nanofibers on osteogenesis of mesenchymal stem cells in vitro and bone regeneration in vivo

Among a variety of polymers, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a microbial polyester, with biodegradable, nonantigenic, and biocompatible properties, is attracting more and more attention in tissue engineering. Hydroxyapatite (HA), similar to the mineral component of natural bone, is known to be osteoconductive, nontoxic, and noninflammatory. In this study, aligned and random-oriented PHBV nanofibrous scaffolds loaded with HA nanoparticles were fabricated through electrospinning technique. Mesenchymal stem cells (MSCs) derived from rat bone marrow were used to investigate the effects of HA and orientation of fibers on cell proliferation and differentiation in vitro. Cell proliferation tested with CCK-8 assay indicated that the MSCs attached and proliferated more favorably on random-oriented PHBV nanofibrous meshes without HA. After one, two and four weeks of cell seeding, osteogenic markers including alkaline phosphate (ALP), osteocalcin (OCN), and mineralized matrix deposits were detected, respectively. The results indicated that the introduction of HA could induce MSCs to differentiate into osteoblasts. Moreover, 3D PHBV/HA scaffolds made from aligned and random-oriented nanofibers were implanted into critical-sized rabbit radius defects and exhibited significant effects on the repair of critical bone defects, implying their promising applications in bone tissue engineering.

Hydroxylapatite nanoparticles: fabrication methods and medical applications

Hydroxylapatite (or hydroxyapatite, HAp) exhibits excellent biocompatibility with various kinds of cells and tissues, making it an ideal candidate for tissue engineering, orthopedic and dental applications. Nanosized materials offer improved performances compared with conventional materials due to their large surface-to-volume ratios. This review summarizes existing knowledge and recent progress in fabrication methods of nanosized (or nanostructured) HAp particles, as well as their recent applications in medical and dental fields. In section 1, we provide a brief overview of HAp and nanoparticles. In section 2, fabrication methods of HAp nanoparticles are described based on the particle formation mechanisms. Recent applications of HAp nanoparticles are summarized in section 3. The future perspectives in this active research area are given in section 4.