Material characterization of microsphere-based scaffolds with encapsulated raw materials

Abstract

“Raw materials,” or materials capable of serving both as building blocks and as signals, which are often but not always natural materials, are taking center stage in biomaterials for contemporary regenerative medicine. In osteochondral tissue engineering, a field leveraging the underlying bone to facilitate cartilage regeneration, common raw materials include chondroitin sulfate (CS) for cartilage and β-tricalcium phosphate (TCP) for bone. Building on our previous work with gradient scaffolds based on microspheres, here we delved deeper into the characterization of individual components. In the current study, the release of CS and TCP from poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds was evaluated over a time period of 4 weeks. Raw material encapsulated groups were compared to ‘blank’ groups and evaluated for surface topology, molecular weight, and mechanical performance as a function of time. The CS group may have led to increased surface porosity, and the addition of CS improved the mechanical performance of the scaffold. The finding that CS was completely released into the surrounding media by 4 weeks has a significant impact on future in vivo studies, given rapid bioavailability. The addition of TCP seemed to contribute to the rough external appearance of the scaffold. The current study provides an introduction to degradation patterns of homogenous raw material encapsulated scaffolds, providing characterization data to advance the field of microsphere-based scaffolds in tissue engineering.

Biomimetic gradient scaffold of collagen–hydroxyapatite for osteochondral regeneration

“…3,7 However, there are few studies reported in the literature describing gradient scaffolds for osteochondral regeneration, and most are still at a very preliminary experimental stage. 3,[8][9][10][11][12][13] Hence, there is still an unmet clinical and scientific need for an improved approach for the treatment of osteochondral defects. 6 The aim of this study was to design and fabricate a highly porous, integrative and cell-instructive scaffold, using a continuum model and selected biomaterials to fulfil the necessary features of the complex osteochondral tissue interface.…”

Microsphere-based scaffolds encapsulating tricalcium phosphate and hydroxyapatite for bone regeneration

“…Scaffolds were prepared from the microspheres using our previously established technology [33, 22, 27, 35, 37, 38]. In brief, lyophilized microspheres (50–70 mg) were dispersed in DI H 2 O and loaded into a syringe.…”

“…Among all possible testing modalities, compression at a 10%/min strain rate provides the most valuable information in terms of achieving high strain levels to view the entire stress-strain profile, which cyclic testing and stress relaxation/creep testing do not provide, and moreover a reproducible elastic modulus can be obtained without preconditioning as we have done in the past [40]. Compressive moduli of elasticity were calculated from the initial linear regions, i.e., at ~5% strain, of the stress-strain curves as described previously [33, 27, 35, 26, 37, 38]. …”

Recent advances on gradient hydrogels in biomimetic cartilage tissue engineering

“…We still need to develop efficient ways of generating gradients of other important bioactive molecules, such as oxygen tension gradient 68 and gradients of insulin, ascorbate, and glucose 69 . Another interesting aspect is establishing gradients of ‘raw materials’ such as chondroitin sulfate incorporated into the hydrogel 70 – 72 . Also, more work needs to be done on control of the localized molecular orientation, such as different alignments of collagen fibers in cartilage zones 16 .…”