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The sol-to-gel transition occurring at around body temperature makes the MPEG-PCL diblock copolymer an ideal candidate material for use as an injectable in situ-forming gel containing human adipose tissue-derived stem cells (hADSCs). The sol can be prepared at room temperature, and the gel forms at body temperature. Solutions of the copolymer containing hADSCs and osteogenic factors injected into rats formed gel scaffolds at the injection sites. The gels thus formed showed the interconnective pore structure required to support growth, proliferation, and differentiation of hADSCs. Bromodeoxyuridine-labeled hADSCs were confirmed to be present in gels formed in vivo. Bone formation was observed only in gel implants containing both hADSCs and osteogenic factors. Subcutaneous implantation of the in situ-forming gel scaffold demonstrated that hADSCs embedded in the gel stimulated much lower host tissue responses than did the gel alone, probably because of the unique immunomodulatory properties of hADSCs. In conclusion, our data on hADSCs embedded in an in situ gel scaffold suggest that this formulation may provide numerous benefits as a noninvasive alternative for tissue-engineered bone formation.

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Surface-modified titanium (Ti) samples with hydroxyapatite (HAp) and heparin (Hep)-bone morphogenetic protein-2 (BMP-2) complex (Ti/HAp/Hep/BMP-2) were prepared, and their efficacies on the enhancements of bone formation and osseointegration in vitro and in vivo were examined as compared to Ti/HAp and Ti/Hep/BMP-2. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle goniometry. In vitro studies revealed that MG-63 human osteosarcoma cell lines grown on Ti/HAp/Hep/BMP-2 increased the amounts of alkaline phosphatase (ALP) activity, calcium deposition and the levels of OCN mRNA gene expression as compared to those grown on Ti/HAp, Ti/Hep/BMP-2 or pristine Ti. Moreover, Ti/HAp/Hep/BMP-2 exhibited higher bone volume (BV), bone volume/tissue volume (BV/TV), removal torque value and bone-implant contact (BIC) than Ti/HAp, Ti/Hep/BMP-2 or pristine Ti in vivo. Histological evaluations showed that many desirable features of bone remodelling existed at the interface between Ti/HAp/Hep/BMP-2 and the host bone. Consequently, Ti/HAp/Hep/BMP-2 may have potential for clinical use as dental or orthopaedic implants.

In this study, we prepared an injectable drug delivery depot system based on a visible light-cured glycol chitosan (GC) hydrogel containing paclitaxel (PTX)-complexed beta-cyclodextrin (β-CD) (GC/CD/PTX) for ovarian cancer (OC) therapy using a tumor-bearing mouse model. The hydrogel depot system had a 23.8 Pa of storage modulus at 100 rad/s after visible light irradiation for 10 s. In addition, GC was swollen as a function of time. However, GC had no degradation with the time change. Eventually, the swollen GC matrix affected the releases of PTX and CD/PTX. GC/PTX and GC/CD/PTX exhibited a controlled release of PTX for 7 days. In addition, GC/CD/PTX had a rapid PTX release for 7 days due to improved water solubility of PTX through CD/PTX complex. In vitro cell viability tests showed that GC/CD/PTX had a lower cell viability percentage than the free PTX solution and GC/PTX. Additionally, GC/CD/PTX resulted in a superior antitumor effect against OC. Consequently, we suggest that the GC/CD system might have clinical potential for OC therapy by improving the water solubility of PTX, as PTX is included into the cavity of β-CD.

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