E Sle Kim

In vivo efficacy of paclitaxel-loaded injectable in situ-forming gel against subcutaneous tumor growth.

Injectable in situ-forming gels have received considerable attention as localized drug delivery systems. Here, we examined a poly(ethylene glycol)-b-polycaprolactone (MPEG-PCL) diblock copolymer gel as an injectable drug depot for paclitaxel (Ptx). The copolymer solution remained liquid at room temperature and rapidly gelled in vivo at body temperature. In vitro experiments showed that Ptx was released from MPEG-PCL copolymer gels over the course of more than 14 days. Experiments employing intratumoral injection of saline (control), gel-only, Taxol, or Ptx-loaded gel into mice bearing B16F10 tumor xenografts showed that Ptx-loaded gel inhibited the growth of B16F10 tumors more effectively than did saline or gel alone. Further, intratumoral injection of Ptx-loaded gel was more efficacious in inhibiting the growth of B16F10 tumor over 10 days than was injection of Taxol. A histological analysis demonstrated an increase in necrotic tissue in tumors treated with Ptx-loaded gel. In conclusion, our data show that intratumoral injection of Ptx-loaded MPEG-PCL diblock copolymer yielded an in situ-forming gel that exhibited controlled Ptx release profile, and that was effective in treating localized solid tumors.

Small intestine submucosa sponge for in vivo support of tissue-engineered bone formation in the presence of rat bone marrow stem cells

The aim of the current study was to visualize new bone formed in vivo on a small intestine submucosa (SIS) sponge used as a tissue-engineered scaffold for the repair of damaged bone. The SIS sponge provided a three-dimensional pore structure, and supported good attachment and viability of rat bone marrow stem cells (rBMSCs). To examine bone regeneration, we prepared full-thickness bilateral bone defects in the rat crania, and then treated the defects with an implanted SIS sponge or PGA mesh without or with rBMSCs, or left the defects untreated. Bone defects were evaluated by micro-CT and histologically after 2 and 4 weeks. Micro-CT demonstrated a trend toward a decrease in bone void in both the SIS sponge and SIS sponge/rBMSCs groups compared to the control and PGA mesh groups. At 4 weeks, bone formation in defects containing SIS sponge/rBMSCs was significantly greater than in all other groups. A histological analysis after 2 and 4 weeks of implantation showed localized collagen and osteocalcin deposition on SIS sponges and SIS sponges with rBMSCs. These in vivo results indicate that the SIS sponge, implanted at bone-removal defects, facilitated bone regeneration.

In vitro and in vivo release of albumin from an electrostatically crosslinked in situ-forming gel

Delivery systems capable of maintaining a sustained release of protein drugs at specific sites can potentially circumvent problems of toxicity and subtherapeutic local dosing levels associated with systemic administration. Here, we used bovine serum albumin (BSA) as a test protein to explore the potential utility of an in situ-forming gel consisting of sodium carboxymethylcellulose (CMC) and polyethyleneimine (PEI) as a depot for protein drugs. BSA-FITC-loaded CMC/PEI solutions were easily prepared and remained liquid at room temperature. When these solutions were subcutaneously injected into rats, they immediately gelled, forming an electrostatically crosslinked three-dimensional network structure that showed sustained release of BSA-FITC for 15 days in vitro and in vivo. No BSA-FITC remained in CMC/PEI gels after this time, indicating complete release of protein cargo. The sustained release of BSA-FITC was also monitored by real-time molecular imaging, which showed that BSA-FITC bioavailability in BSA-FITC-loaded CMC/PEI gels was more than twice that of BSA-FITC-only solutions. CMC/PEI gels provoked only a modest inflammatory response. Collectively, our results show that the CMC/PEI gel described here could serve as a minimally invasive therapeutics depot with numerous benefits compared to orally or intravenously administered drugs.

In vivo release of bovine serum albumin from an injectable small intestinal submucosa gel.

We aimed to develop a delivery system capable of maintaining a sustained release of protein drugs at specific sites using potentially biocompatible biomaterials. Here, we used bovine serum albumin (BSA) as a test protein to explore the potential utility of an injectable small intestine submucosa (SIS) as a depot for protein drugs. The prepared SIS powder was dispersed in PBS. The SIS suspension easily entrapped BSA in pharmaceutical formulations at room temperature. When this was suspension subcutaneously injected into rats, it gelled, forming an interconnecting three-dimensional network SIS structure to allow BSA to penetrate through it. The amount of BSA-FITC released from the SIS gel was determined in rat plasma and monitored by real-time in vivo molecular imaging. The data indicated the sustained release of BSA-FITC for 30 days in vivo. In addition, SIS gel provoked little inflammatory response. Collectively, our results show that the SIS gel described here could serve as a minimally invasive therapeutics depot with numerous benefits compared to other injectable biomaterials.

Potential induction of rat muscle‐derived stem cells to neural‐like cells by retinoic acid

Several recent studies have demonstrated that stem cell differentiation can be generated by derivatives of retinoic acid. In this study we chose retinoic acid (RA) for inducing neural differentiation of rat muscle‐derived stem cells (rMDSCs). rMDSCs were pre‐induced with 10 ng/ml basic fibroblast growth factor (bFGF) and then treated with 2 μM RA. After stimulation, RA induced rMDSCs to have a neural‐like morphology after 1–7 days of in vitro differentiation. In the results of immunocytochemistry, rMDSC treated with RA showed abundant positive cells against the neuronal markers neuronal‐specific enolase (NSE) and tubulin‐βIII (Tuj1). Also, 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPase)‐positive cells were observed, indicating oligodendrocyte lineage cells. However, positive cells against glial fibrillary acidic protein (GFAP), marker of astrocytes, were not detected. The mRNA profile of these cells included higher expression of NSE compared with those of non‐treated cells in real‐time PCR. From the data in this work, we suggest that rMDSCs can trans‐differentiate into a neural‐like phenotype under the RA conditions. Copyright

Injectable CMC/PEI gel as an in vivo scaffold for demineralized bone matrix.

A number of materials have been considered as sources of grafts to repair bone defects. Here, we examined the possibility of creating in situ-forming gels from sodium carboxymethylcellulose (CMC) and poly(ethyleneimine) (PEI) for use as an in vivo carrier of demineralized bone matrix (DBM). The interaction between anionic CMC and cationic PEI was examined by evaluating phase transition behavior and viscosity of CMC solutions containing 0-30 wt% PEI. CMC solutions containing 10 wt% PEI exhibited a sol-to-gel phase transition at temperatures greater than 35 degrees C. The phase transition is caused by electrostatic crosslinking of the CMC/PEI solution to form a gel with a three-dimensional network structure. In situ-formed gel implants were successfully fabricated in vivo by simple subcutaneous injection of the CMC/PEI (90/10) solution (with and without DBM) into Fisher rats. The resulting in situ-formed implant maintained its shape for 28 days in vitro and in vivo. Our results show that in situ-forming CMC/PEI gels can serve as a DBM carrier that can be delivered with a minimally invasive procedure.

Induction of neurogenesis in rat bone marrow mesenchymal stem cells using purine structure-based compounds

Rat bone marrow stem cells (rBMSCs) in the presence of chemical molecules were differentiated into neurons.

Preparation and characterization of self-emulsified docetaxel

The aim of this paper was to prepare a self-microemulsifying docetaxel (Dtx) using PLGA, Tetraglycol, Labrasol, and Cremophor ELP. The prepared Dtx-loaded self-microemulsifying system (SMES) showed the initial size of the range of 80-100nm with narrow size distribution and the negative zeta-potential values. Its morphology was a spherical shape by atomic force microscopy. In experiment of stability, Dtx-loaded SMES prepared in DW and BSA condition showed good stability at 37°C for 7 days. The viability of the B16F10 cells incubated with Dtx-loaded SMES, Dtx-solution, and Taxol were decreased as a function of incubation time. In conclusion, we confirmed that Dtx-loaded SMES showed an inhibitory effect for proliferation of B16F10 melanoma cells.

In vivo release of bovine serum albumin from a small intestinal submucosa gel

Small intestinal submucosa (SIS) solution was manufactured and injected. In vivo sustained release of BSA-FITC from the SIS gels was observed.

Electrospun chitosan nanofiber for tissue engineering

Since the effective use of biomaterials as a scaffold requires good biocompatibility and biofunctionality, we examined the properties of electrospun chitosan nanofiber scaffold prepared by electrospining for tissue engineering.