Implantable sandwich PHBHHx film for burst-free controlled delivery of thymopentin peptide

Sustained release and non-parental formulations of peptides and protein drugs are highly desirable because of enhanced therapeutic effects as well as improved patient compliance. This is especially true for small peptides such as thymopentin (TP5). To this end, implantable sandwich poly (hydroxybutyrate--hydroxyhexanoate) (PHBHHx) films were designed to prolong release time and to inhibit burst release phenomenon of TP5 by a simple volatilization method. release studies revealed that sandwich films had nearly no burst release. release time of sandwich films was prolonged to 42 days. Pharmacodynamic evaluation demonstrated that TP5 sandwich films significantly increased survival rates in a rat immunosuppressive model and normalized CD4/CD8 values. These results suggest that TP5 released from sandwich films can attenuate cyclophosphamide's immunosuppressive activity, and possibly achieve results comparable to daily TP5 injection therapy. Thus, sandwich PHBHHx films show excellent potential as a sustained, burst-free release system for small molecular weight, hydrophilic peptide drugs.

Development of tumor targeting PHBHHx nanoparticles by PhaP mediated immobilization of EGFR-targeting peptide / 生物工程学报

PHA granule binding protein phasin (PhaP) has a high affinity for hydrophobic materials and can bind to hydrophobic polymers via strong hydrophobic interaction. In this study, an EGFR-targeting peptide (ETP) was fused with PhaP and the fusion protein ETP-PhaP was produced in recombinant Escherichia coli BL21 (DE3) (pPI-ETP-P) and then purified by Ni affinity purification. The tumor targeting PHBHHx nanoparticles were developed based on PhaP mediated ETP immobilization and the cellular uptake of the ETP-PhaP modified PHBHHx NPs and none modified PHBHHx NPs by cervical cancer cell lines SiHa (EGFR over expressed) and CaSKi (EGFR low expressed) were analyzed. The purified ETP-PhaP could be adsorbed onto the hydrophobic surface of PHBHHx NPs. The ETP-PhaP modified PHBHHx NPs could target to EGFR over expressed cervical cancer cells SiHa more efficiently than to the EGFR low expressed CaSKi cells. These results demonstrated the advantage in effectiveness and convenience of PhaP mediated ETP adsorption on PHBHHx nanoparticles, providing a novel strategy for hydrophobic nanocarrier surface modification.

Study on PHBHHx co-cultured with mouse induced pluripotent stem cells for use as myocardial patches in vitro / 中华胸心血管外科杂志

Objective To study the effect of polymer material on adhesion , proliferation and differentiation of mouse in-duced pluripotent stem cells via co-culturing in vitro, to find a suitable polymeric biomaterials for miPSCs attachment , prolifera-tion and differentiation , forming myocardial patches as a new repair method for myocardial infarction .Methods miPSCs were recovered, passaged and cultured with PHBHHx two-dimension films and PHBHHx three-dimension films together.The mor-phology of miPSCs attached on the films was visualized under scanning electron microscope ( SEM) .The mouse induced pluri-potent stem cells were induced by differentiation medium that containing vitamin C .Control group did not add any inducer.The survival and differentiation of miPSCs were observed through immunofluorescence and flow cytometry .Results MiPSCs can grow, proliferate and differentiate on PHBHHx films both two-dimension and three-dimension.Vitamin C, as a favourable in-ducer, can markedly improve the efficiency of miPSCs differentiation of cardiomyocytes on PHBHHx films .Immunofluorescence results demonstrated positive cTnT expression.Flow cytometry measured cTnT expression: Vitamin C inducer group(47.54 ± 1.46)%>without any inducer group(7.02 ±0.95)%(PPHBHHx two-dimensional films(53.31 ±1.41)%>traditional cell culture(47.54 ±1.46)%(P<0.05).Conclusion iPSCs can ad-here, survive and differentiate on the PHBHHx film.Vitamin C, as a favourable inducer, can markedly improve the efficiency of miPSCs differentiation of cardiomyocytes .Relative to PHBHHx two-dimensional film culture and traditional culture , the three-dimensional PHBHHx film culture has a great advantage in the process of miPSCs differentiating into myocardial cells .

Heterotopic osteogenesis in vivo of PHBHHx and human umbilical cord mesenchymal stem cells / 重庆医学

Objective To explore the ability for constructing tissue engineering bone in vivo in complex scaffolds with PHB‐HHx as the scaffolds material and human umbilical cord mensenchymal stem cells (hUCMCs) as the seed cells .Methods hUCM‐SCs were inoculated into PHBHHx scaffolds to induce osteogenesis culture in vivo for two weeks ,the the induced group was the experimental group and those without instilling hUCMCs served as the control group ,the nude mouse subcutaneous implantation was performed .Then taking material at 1 ,3 ,5 months after implantation in vivo was performed for conducting HE ,collagenⅠim‐munohistochemical ,alkaline phosphatase staining and RT‐PCR .Results hUCMSCs showed good cellular adsorbability .The size and form in the experimental group basically maintained the original status ,and the osteogenesis specific indicators were positive ;but the control group did not keek the original status ,its volume was gradually shrunk until complete degradation ,and the osteogen‐esis specific indicators were negative .Conclusion The PHBHHx scaffolds combined with hUCMSCs has the capability of in vivo heterotopic constructing tissue engineering bone in nude mouse by in vitro osteogenic induction .

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)-based scaffolds for tissue engineering

Development and selection of an ideal scaffold is of importance for tissue engineering. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biocompatible bioresorbable copolymer that belongs to the polyhydroxyalkanoate family. Because of its good biocompatibility, PHBHHx has been widely used as a cell scaffold for tissue engineering. This review focuses on the utilization of PHBHHx-based scaffolds in tissue engineering. Advances in the preparation, modification, and application of PHBHHx scaffolds are discussed.

Compatibility of human umbilical vein endothelial cells and surface-modified PHBHHx film in vitro / 解剖学报

Objective To evaluate the growing condition of human umbilical vein endothelial cells (HUVECs), which were cultured on the membrane of different component, such as Chinese medicine, before or after the alkali treatment of 3-hydroxybutyrate-co-3-hydroxyhexanoate copolyesters (PHBHHx) and the biocompatibility between PHBHHx flim and endothelial cell. Methods The HUVECs were harvested by Baudine method,and identified by immunohistochemical method.Then the HUVECs of third passage were inoculated on the material surface and cultured for 8 hours,12 hours and 24 hours. After that, the morphology of HUVECs on different surfaces were observed by scanning electron microscopy, the distribution condition on different membranes were compared by cell-labeling immunofluorescence, and the cell viabilities of all groups were detected by MTT method. Results The HUVECs were successfully separated,and immunohistochemistry staining of FLK-1 and factor Ⅷ was positive.The result of HUVECs culture showed that cells on the material surface growed well, and proliferated significantly. The MTT analysis showed that the PHBHHx film of surface modification and adding some certain proportion of Chinese medicine could promote the growth and proliferation of HUVECs in vitro,and the cells were thriving, full shape, distribution on the surface by scanning electron microscopy and fluorescence microscopy.Conclusion The PHBHHx film of surface modification and containing certain proportion of Chinese medicine coating had good compatibility of HUVECs, which was favourable to cell growth, adherence and proliferation in vitro.