Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) supports adhesion and migration of mesenchymal stem cells and tenocytes

AIM: To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair.METHODS: The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal stem cells (hMSC) was explored by monitoring adhesive characteristics on films of varying weight/volume ratios coupled to a culture atmosphere of either 21% O₂ (air) or 2% O₂ (physiological normoxia). The diameter and stiffness of PHBHHx films was established using optical coherence tomography and mechanical testing, respectively.RESULTS: Film thickness correlated directly with weight/volume PHBHHx (r² = 0.9473) ranging from 0.1 mm (0.8% weight/volume) to 0.19 mm (2.4% weight/volume). Film stiffness on the other hand displayed a biphasic response which increased rapidly at values > 1.6% weight/volume. Optimal cell attachment of rT required films of ≥ 1.6% and ≥ 2.0% weight/volume PHBHHx in 2% O₂ and 21% O₂ respectively. A qualitative adhesion increase was noted for hMSC in films ≥ 1.2% weight/volume, becoming significant at 2% weight/volume in 2% O₂. An increase in cell adhesion was also noted with ≥ 2% weight/volume PHBHHx in 21% O₂. Cell migration into films was not observed.CONCLUSION: This evaluation demonstrates that PHBHHx is a suitable polymer for future cell/polymer replacement strategies in tendon repair.