Effects of designed PLLA and 50:50 PLGA scaffold architectures on bone formation in vivo

Abstract

Biodegradable porous scaffolds have been investigated as an alternative approach to current metal, ceramic, and polymer bone graft substitutes for lost or damaged bone tissues. Although there have been many studies investigating the effects of scaffold architecture on bone formation, many of these scaffolds were fabricated using conventional methods, such as salt leaching and phase separation, and were constructed without designed architecture. To study the effects of both designed architecture and material on bone formation, we designed and fabricated three types of porous scaffold architecture from two biodegradable materials, poly (L-lactic acid) (PLLA) and 50:50Poly (lactic-co-glycolic acid) (PLGA) using image based design and indirect solid freeform fabrication techniques, seeded them with bone morphogenic protein-7 transduced human gingival fibroblasts and implanted them subcutaneously into mice for 4 and 8 weeks. Micro-computed tomography data confirmed that the fabricated porous scaffolds replicated the designed architectures. Histological analysis revealed that the 50:50PLGA scaffolds degraded and did not maintain their architecture after 4 weeks. The PLLA scaffolds maintained their architecture at both time points and showed improved bone ingrowth which followed the internal architecture of the scaffolds. Mechanical properties of both PLLA and 50:50PLGA scaffolds decreased, but PLLA scaffolds maintained greater mechanical properties than 50:50PLGA after implantation. The increase of mineralized tissue helped to support mechanical properties of bone tissue and scaffold constructs from 4 to 8 weeks. The results indicated the importance of choice of scaffold materials and computationally designed scaffolds to control tissue formation and mechanical properties for desired bone tissue regeneration.

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

“…Saito et al (2013; has studied the effect of the strut size on in-vivo degradation of poly(L-lactic acid) and PLGA three-dimensional porous scaffolds and demonstrated that scaffolds with larger struts (~0.9 mm) degrade more rapidly than scaffolds with smaller struts (~0.4 mm). The present study elucidates the relationship between the strut size, scaffold architecture, and the stiffness of the scaffold during degradation.…”

The effects of poly L-lactic acid nanofiber scaffold on mouse spermatogonial stem cell culture

“…Although several reports have described culturing various stem cells within the 3D scaffolds, 23,[73][74][75][76][77] the result of such cultures has most commonly been stem cell differentiation. Nur et al 23 cultured embryonic stem cells on a 3D nanofibrillar surface and observed proliferation with self-renewal.…”

Nano-ceramic Composite Scaffolds for Bioreactor-based Bone Engineering

“…Notably, more pronounced mineralization was found in the scaffold interior than on the scaffold surfaces. This finding is in contrast to static cultured tissue-engineered constructs in which cell ingress into the interior is reportedly limited to a depth of several hundred microns [13,27,49,51]. Further actin and nucleus staining of HMSCs on PLAGA/n-HA scaffolds suggested a greater number of cells were distributed uniformly in the interior of scaffolds than on the surface of scaffolds (Fig.…”

“…Although in vitro results have been published in which cells are capable of penetrating the interior of polymer/ ceramic scaffolds [24], these scaffolds alone are often only able to induce new bone tissue development in vivo at the scaffold surface [13,27,51]. This issue may be overcome by first cellularizing the scaffold with stem cells in vitro [17].…”