Injectable soft-tissue augmentation by tissue engineering and regenerative medicine with human mesenchymal stromal cells, platelet-rich plasma and hyaluronic acid scaffolds

Background aims The aim of this study was to evaluate the possibility of soft-tissue augmentation adopting tissue engineering and regenerative medicine (TERM) technology for a longer duration of injected implants. Methods TERM is the combination and re-organization of three types of injection materials to regenerate organs and tissues: (i) living cells, including cultured human mesenchymal stromal cells (hMSCs) and human fibroblasts (hFibro); (ii) scaffolds of hyaluronic acid (HA); and (iii) growth factors of platelet-rich plasma (PRP). The experimental combinations were as follows: HA, HA/hFibro, HA/hMSCs, HA/PRP, HA/PRP/hFibro and HA/PRP/hMSCs. These were injected intradermally into immunodeficient rats and evaluated by histologic analysis, percentage of original volume and maintenance volume. Results The percentage of original volume values at 14 days were 0.02 0.01% (HA), 0.20 0.03% (HA/hFibro), 0.50 0.02% (HA/hMSCs), 11.66 1.81% (HA/PRP), 24.36 8.97% (HA/PRP/hFibro) and 28.04 4.11% (HA/PRP/hMSCs), respectively. There were significant differences between groups with and without PRP. Regarding maintenance volume values, HA/PRP, HA/PRP/hFibro and HA/PRP/hMSCs from 7 to 14 days were also higher, at 46.25 1.21%, 78.39 2.90% and 88.81 5.97%, respectively. HA/PRP/hMSCs groups maintained the shape and dimensions of the injected implant, indicating that the injected cells produced type I collagen. Conclusions The findings suggest that a soft tissue-engineered procedure with MSCs may be useful for longer lasting soft-tissue augmentation.