Study On A Novel Terpolyester Poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) For Possible Application As A Skin Tissue Engineering Material

Polyhydroxyalkanostes (PHA) as a family of biodegradable and biocompatible polymers have been demonstrated to have bio-implant applications. A novel PHA terpolymer abbreviated as PHBVHHx, consisting of 3-hydroxybutyrate, 3-hydroxyvalerate and 3-hydroxyhexanoate that can be produced by recombinant microorganisms, was found to have proper thermo- and mechanical properties for possible skin tissue engineering, as demonstrated by its strong ability to support the growth of human keratinocyte cell line HaCaT. As demonstrated in this study, HaCaT cells showed the strongest viability and the highest growth density on PHBVHHx film compared with polylactic acid (PLA), polyhydroxybutyrate (PHB), PHBV copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, PHBHHx copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate and P3HB4HB copolymer consisting of 3-hydroxybutyrate and 4-hydroxybutyrate, even the tissue culture plates were grown with less HaCaT cells compared with that on PHBVHHx. To understand its superior biocompatibility, PHBVHHx nanoparticles ranging from 200-450 nm were prepared. It was found that the nanoparticles could increase the cellular activities by stimulating a rapid increase of cytosolic calcium influx in HaCaT cells, leading to enhanced cell growth. At the same time, 3-hydroxybutyrate (HB), a degradation product and the main component of PHBVHHx, was also shown to promote HaCaT proliferation. Morphologically, under the same preparation conditions, PHBVHHx film showed the most obvious surface roughness under atomic force microscopy (AFM), accompanied by the lowest surface energy compared with all other well studied biopolymers tested above. These results explained the superior ability for PHBVHHx to grow skin HaCaT cells. Therefore, PHBVHHx possesses the suitability to be developed into a skin tissue engineering material.