Evaluation of the donor cell contribution in rhBMP‐2 mediated bone formation with chitosan thermogels using fluorescent protein reporter mice

Abstract

Our current understanding regarding the contribution of donor cells in growth factor and cell based tissue regeneration strategies is limited. The present study attempts to utilize fluorescent protein reporter mice [Col3.6Topaz (enhanced yellow fluorescent protein, EYFP) as host and Col3.6Cyan (enhanced cyan fluorescent protein, ECFP) as donor] to determine donor cell contribution in bone regeneration using a bilateral calvarial defect model. Thermogelling chitosan hydrogels (Chi-AHP) were used as bone marrow stromal cell (BMSC) delivery vehicle in the presence and absence of recombinant human bone morphogenetic protein-2 (rhBMP-2). Co-delivery of rhBMP-2 and donor BMSCs led to a significant increase in bone formation indicating the potential of using the combination approach for improved regeneration. On a cellular level, presence of rhBMP-2 resulted in an increased host cell derived osteoblast infiltration at 8 weeks. However, the new mineralized tissue presented two distinct morphological features based on its cellular origin. Regenerated tissue associated with ECFP positive donor cells showed a woven bone-like structure with diffuse alizarin complexone (AC) label and minimal tartrate resistant acid phosphatase (TRAP) activity, indicating the presence of immature early osteoblast cells depositing mineralized tissue without progressing to a mature lamellar bone. Host derived bone showed sharp mineralization line (AC), strong alkaline phosphatase (ALP) and TRAP activity, indicating the presence of actively mineralizing and remodeling, mature lamellar bone matrix. The study demonstrated the remarkable potential of transgenic reporters to improve our understanding of donor cell contribution during bone formation.

Retracted: MicroRNA‐539 promotes osteoblast proliferation and differentiation and osteoclast apoptosis through the AXNA‐dependent Wnt signaling pathway in osteoporotic rats

“…Also, BGP and ALP genes play critical roles in osteoblast differentiation . Well‐Known as markers of bone formation and disruption, strong ALP and TRAP activity suggests active mineralizing and remodeling as well as mature lamellar bone matrix . According to a previous study, ALP activity was increased with the combination of BMP‐2 and dexamethasone synergistically through the activation of signal transducer and activator of transcription 3 (STAT3) signaling pathway in C3H10T1/2 cells .…”

“…39 Well-Known as markers of bone formation and disruption, strong ALP and TRAP activity suggests active mineralizing and remodeling as well as mature lamellar bone matrix. 40,41 According to a previous study, ALP activity was increased with the combination of BMP-2 and dexamethasone synergistically through the activation of signal transducer and activator of transcription 3 (STAT3) signaling pathway in C3H10T1/2 cells. 42 It has been reported that with elevated ALP activity and enhanced mineralization, appropriate plasma irradiation promotes differentiation of osteoblasts, which might be a potential target for bone regeneration.…”

Bone Morphogenic Protein and Mesenchymal Stem Cells to Regenerate Bone in Calvarial Defects: A Systematic Review

“…In 2016, Gohil, S. V. et al [ 11 ] investigated the viability of utilizing calcium-hydroxyapatite (Chi-AHP) and Chi-AHP with rhBMP-2 for promoting bone regeneration. After four weeks, the Chi-AHP-implanted defect sites exhibited restricted cellular infiltration but no mineralized tissue formation or ALP/TRAP activity.…”

“…Full-text articles excluded, with reasons (n = 17) No use of MSCs (5). No BMP therapy (11). Reviews (1).…”

“…In addition, it was discovered that scaffolds pretreated with a combination of Wnt3a and BMP-2 promoted enhanced recruitment of endogenous osteoprecursors and osteogenic potential. The previous observation suggests the potential application of a fusion of growth factor delivery techniques in bone tissue engineering, thereby accelerating the process of bone regeneration.In 2016, Gohil, S. V. et al[11] investigated the viability of utilizing calcium-hydroxyapatite (Chi-AHP) and Chi-AHP with rhBMP-2 for promoting bone regeneration. After four weeks, the Chi-AHP-implanted defect sites exhibited restricted cellular infiltration but no mineralized tissue formation or ALP/TRAP activity.…”