The role of transduced bone marrow cells overexpressing BMP-2 in healing critical-sized defects in a mouse femur

Abstract

The role that transduced mouse bone marrow stromal cells (mBMSCs) engineered to overexpress human bone morphogenetic protein 2 (BMP-2) play in healing critical-sized skeletal defects is largely unknown. We evaluated the interaction between host osteoprogenitor cells and donor mBMSCs transduced with either a lentiviral (LV) vector-expressing red fluorescent protein (RFP) with or without BMP-2 that were implanted into a critical-sized femoral defect. Radiographs taken at the time of killing were evaluated using a five-point scaled scoring system. Frozen histologic sections were analyzed to assess both the transduced cells' role in bone repair and the local osteoprogenitor response. There was complete radiographic bridging in 94% of group I (LV-RFPch-BMP-2-cmyc) and 100% of group III (recombinant human BMP-2) specimens. Radiographs demonstrated a lack of healing in group II (LV-RFPch). Mouse BMSCs transduced with an LV-RFPch-BMP-2 vector were able to induce host cells to differentiate down an osteoblastic lineage and heal a critical-sized defect. However, the donor cells appeared to be functioning as a delivery vehicle of BMP-2 rather than actually differentiating into osteoblasts capable of participating in bone repair as evidenced by a lack of colocalization of the transduced cells to the sites of skeletal repair where the host progenitor cells were found.

Genetic modification of scAAV‐equine‐BMP‐2 transduced bone‐marrow‐derived mesenchymal stem cells before and after cryopreservation: An “off‐the‐shelf” option for fracture repair

“…We first observed that scAAV‐equine‐BMP‐2 transduced cells produced significantly more BMP‐2 protein than any other treatment group (Figure ). This is in agreement with several other groups utilizing a traditional ex vivo transduction technique . Importantly, the one‐time scAAV‐equine‐BMP‐2 transduction produced significantly more protein than what is clinically available today without repeat administration of rhBMP‐2.…”

“…This is in agreement with several other groups utilizing a traditional ex vivo transduction technique. 33,34 Importantly, the one-time scAAV-equine-BMP-2 transduction produced significantly more protein than what is clinically available today without repeat administration of rhBMP-2. While this study did not incorporate the use of a carrier, protein elution from genetically modified cells loaded onto a carrier would be expected to remain unchanged, and protein delivery would then be dependent on cell delivery, and not dictated by hydrolysis and elution characteristics of various scaffolds.…”

Engineering multicellular systems: Using synthetic biology to control tissue self-organization

“…This supports the idea that host cells, even in non-regenerative contexts, can be induced to regenerate and also suggests that engineered cells, with their enhanced communications, could be a suitable medium to overcome the block to regeneration. In another example, mesenchymal stem cells were engineered to overexpress the growth factor BMP-2 to increase bone regeneration responses [39]. These studies represent validation of the idea that engineered cells can be used as the basis for regenerative therapeutic interventions, and lays the foundation for more complex and rational interventions.…”

Comparison of Osteogenesis between Adipose-Derived Mesenchymal Stem Cells and Their Sheets on Poly-ε-Caprolactone/β-Tricalcium Phosphate Composite Scaffolds in Canine Bone Defects

“…A biomimetic periosteum can maintain homeostasis of the cellular microenvironment by delivering growth factors. A previous study showed that paracrine factors of MSCs play a positive role in bone repair [23, 24]. During bone healing, the proliferation and osteoblastic differentiation of endogenous or exogenous MSCs are influenced by various growth factors, among which TGF- β and BMPs play a major role.…”