Cell Therapy for Skin Wound Using Fibroblast Encapsulated Poly(ethylene glycol)-poly(L-alanine) Thermogel

Thermogels that undergo sol-to-gel transition with increasing temperature have been extensively investigated, focusing on the new materials development, transition mechanisms, and new biomedical applications. Polyesters, chitosan, polyphosphazenes, polycarbonates, polycyanoacrylates, polyorthoesters, and polypeptides have been developed as a thermogel.

A simple procedure for encapsulating pharmaceuticals agents including drugs and cells makes the thermogel a promising material for drug delivery and tissue engineering and postsurgical adhesion prevention.

In particular, a thermogel has the advantages of filling irregular-shaped defects and providing a three-dimensional cell growth matrix. Therefore, thermogels have been suggested as a promising platform for an injectable tissue engineering scaffold.The wound healing process in skin includes inflammation, proliferation, and remodeling of the skin tissue. All three phases can overlap during the healing process.

As a new application of a thermogel, a poly-(ethylene glycol)-b-poly(L-alanine) (PEG-L-PA) gel encapsulating fibroblasts was investigated for wound healing. The fibroblasts were encapsulated by the temperature sensitive sol-to-gel transition of the polymer aqueous solution. Under the in vitro three-dimensional (3D) cell culture condition, the PEG-L-PA thermogel was comparable with Matrigel for cell proliferation and was significantly better than Matrigel for collagen types I and III formation. After confirming the excellent 3D microenvironment of the PEG-L-PA thermogel for fibroblasts, in vivo wound healing was investigated by injecting the cell-suspended polymer, aqueous solution on incisions of rat skin, where the cell-encapsulated gel was formed in situ. Compared with the phosphate buffered saline treated system and the cell-free PEG-L-PA thermogel, the cell-encapsulated PEG-L-PA thermogel not only accelerated the wound closure but also improved epithelialization and the formation of skin appendages such as keratinocyte layer (epidermis), hair follicles, and sebaceous glands. The results demonstrate the potential of thermogels for cell therapy as an injectable tissue-engineering scaffold.

Cell Therapy for Skin Wound Using Fibroblast Encapsulated Poly(ethylene glycol)-poly(L-alanine) Thermogel

Eun Jung Yun, Bora Yon, Min Kyung Joo, and Byeongmoon Jeong

Department of Bioinspired Science and Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 120-750,

Korea.

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