Published online Jan 26, 2021. doi: 10.4252/wjsc.v13.i1.115
Peer-review started: August 11, 2020
First decision: October 23, 2020
Revised: November 2, 2020
Accepted: November 17, 2020
Article in press: November 17, 2020
Published online: January 26, 2021
How to manage the damaged tendon is still one of the most challenging problems in orthopedics. With the development of cell culture techniques, medical biomaterials, and implantation techniques, tissue engineering techniques show great potential for tendon repair and regeneration. Type I collagen is a popular natural materials used for tendon tissue engineering. One of the possible practical ways to further enhance tendon repair is to combine a porous collagen sponge scaffold with a suitable growth factor that has an inherent ability to promote the recruitment, proliferation, and tenogenic differentiation of cells.
At present, there is an incomplete understanding of which growth factors are sufficient and optimal for the tenogenic differentiation of stem cells in a porous collagen sponge scaffold.
To identify one or more ideal growth factors that benefit the proliferation or/and tenogenic differentiation of stem cells in a porous collagen sponge scaffold, which will help us better understand the role of growth factors in tendon tissue engineering.
We constructed a 3D culture system based on a type I collagen sponge which is a porous scaffold material. The surface topography of the collagen sponge was observed by scanning electron microscopy. Cell survival on the surfaces of the collagen sponge was assessed by live/dead assay, and the activity of cells was assessed by CCK-8 assay. The mRNA and protein expression levels of related molecules were confirmed by quantitative real-time polymerase chain reaction and Western blot, respectively. The deposited collagen was assessed by Sirius Red staining. Histological analyses were performed to investigate the cell distribution and collagen deposition, which can help us visually understand the changes within the constructs.
Medical type I collagen sponge had a good biocompatibility. Transforming growth factor β1 (TGF-β1) had great promise for the tenogenic differentiation and proliferation of bone marrow mesenchymal stem cells (BMSCs) compared to growth differentiation factor 7 (GDF-7) and insulin-like growth factor 1 (IGF-1) in a monolayer culture (2D) and in a collagen sponge-based 3D culture. Moreover, TGF-β1 promoted more collagen deposition in both the 2D and 3D cultures. In the 2D culture, the proliferation of the BMSCs showed no significant changes compared to the control group after TGF-β1, IGF-1, or GDF-7 treatment. However, TGF-β1 and GDF-7 could increase the cell proliferation in the collagen sponge-based 3D culture. Strangely, we also found more dead cells in the 3D culture where cells were treated with TGF-β1.
TGF-β1 shows great promise for BMSCs compared to GDF-7 and IGF-1 in both 2D and 3D cultures, and the collagen sponge-based 3D culture enhances the tenogenic differentiation of BMSCs well beyond the level of induction in the 2D culture after TGF-β1 treatment.
Based on our results, we believe that TGF-β1 is an ideal growth factor that benefits the tenogenic differentiation of BMSCs in a porous collagen sponge scaffold.