Uncultured Marrow Mononuclear Cells Delivered Within Fibrin Glue Hydrogels to Porous Scaffolds Enhance Bone Regeneration Within Critical-Sized Rat Cranial Defects

Abstract

For bone tissue engineering, the benefits of incorporating mesenchymal stem cells (MSCs) into porous scaffolds are well established. There is, however, little consensus on the effects of or need for MSC handling ex vivo. Culture and expansion of MSCs adds length and cost, and likely increases risk associated with treatment. We evaluated the effect of using uncultured bone marrow mononuclear cells (bmMNCs) encapsulated within fibrin glue hydrogels and seeded into porous scaffolds to regenerate bone over 12 weeks in an 8-mm-diameter, criticalsized rat cranial defect. A full factorial experimental design was used to evaluate bone formation within model poly(L-lactic acid) and corraline hydroxyapatite scaffolds with or without platelet-rich plasma (PRP) and bmMNCs. Mechanical push-out testing, microcomputed tomographical analyses, and histology were performed. PRP showed no benefit for bone formation. Cell-laden poly(L-lactic acid) scaffolds without PRP required significantly greater force to displace from surrounding tissues than control (cell-free) scaffolds, but no differences were observed during push-out testing of coral scaffolds. For bone volume formation as analyzed by microcomputed tomography, significant positive overall effects were observed with bmMNC incorporation. These data suggest that bmMNCs may provide therapeutic advantages in bone tissue engineering applications without the need for culture, expansion, and purification.

Platelet-Rich Plasma in Tissue Engineering: Hype and Hope

“…In a study by Kretlow et al [48] uncultured bone marrow mononuclear cells were delivered in coralline hydroxyapatite scaffolds or poly(L-lactic acid) scaffolds with or without PRP (8.6 ± 3.2-fold platelet enrichment) supplementation. While bone marrow mononuclear cells had a positive effect on bone formation in a critically sized rat cranial defect, PRP supplementation did not improve the outcome in this study.…”

Comparison of Uncultured Marrow Mononuclear Cells and Culture-Expanded Mesenchymal Stem Cells in 3D Collagen-Chitosan Microbeads for Orthopedic Tissue Engineering

“…30 In a critical-sized cranial defect in the rat, porous poly(L-lactic acid) scaffolds laden with uncultured BMMC encapsulated within fibrin gel regenerated significantly greater bone volume than cell-free controls. 27 Other recent studies have shown that 3D ceramic scaffolds directly seeded with autologous sheep bone marrow cells/MSC 12 or unprocessed human bone marrow 31 resulted in similar osteogenic potential and comparable bone formation in subcutaneous ectopic implantation models, compared with the same scaffolds seeded with culture-expanded MSC. In contrast to these reports, it has been reported that in vitro culture-induced osteogenic differentiation of purified human bone marrow-derived MSC seeded onto b-tricalcium phosphate ceramics significantly enhanced subsequent ectopic bone formation, compared with samples implanted with culture-expanded but undifferentiated MSC or directly seeded fresh uncultured BMMC, 32 however, the authors of this study state that only 27% of the BMMCs were able to initially adhere to the particular type of scaffolds used.…”

“…[23][24][25][26] In addition, unpurified marrow fractions may contain osteogenic proteins that can be incorporated into biomaterials and scaffolds. 27 Several previous studies have investigated direct seeding of freshly isolated uncultured bone marrow cells into threedimensional (3D) biomaterials for bone and cartilage tissue engineering. In an ectopic implantation model in mice, direct seeding and expansion of uncultured human 28 or sheep 29 bone marrow mononuclear cells (BMMC) into 3D hydroxyapatite-ceramic scaffolds under perfusion resulted in engineered constructs that formed significantly more bone tissue than scaffolds loaded with 2D culture-expanded bone marrow-derived MSC.…”

Imaging of Poly(α-hydroxy-ester) Scaffolds with X-ray Phase-Contrast Microcomputed Tomography

“…5D, E). 27 The benchtop PC image allowed for the identification of newly formed bone and the remaining PLLA scaffold within the defect, similar to the features detected with the synchrotronbased MIR technique. Fiber structures within the defect could be identified in the PC image (Fig.…”

“…27 One group was enriched with platelet-rich plasma and seeded with bone marrow mononuclear cells. Critical-sized, 8-mm-diameter defects were created in the rat calvarium of male Fisher 344 rats (Harlan Bioproducts) (12 weeks old, 225-249 g) and filled with freshly prepared implants and closed.…”