title: Polypeptide thermogels as a three dimensional culture scaffold for hepatogenic differentiation of human tonsil-derived mesenchymal stem cells.
abstract: Tonsil-derived mesenchymal stem cells (TMSCs) were investigated for hepatogenic differentiation in the 3D matrixes of poly(ethylene glycol)-b-poly(l-alanine) (PEG-L-PA) thermogel. The diblock polymer formed β-sheet based fibrous nanoassemblies in water, and the aqueous polymer solution undergoes sol-to-gel transition as the temperature increases in a concentration range of 5.0-8.0 wt %. The cell-encapsulated 3D matrix was prepared by increasing the temperature of the cell-suspended PEG-L-PA aqueous solution (6.0 wt %) to 37 °C. The gel modulus at 37 °C was about 1000 Pa, which was similar to that of decellularized liver tissue. Cell proliferation, changes in cell morphology, hepatogenic biomarker expressions, and hepatocyte-specific biofunctions were compared for the following 3D culture systems: TMSC-encapsulated thermogels in the absence of hepatogenic growth factors (protocol M), TMSC-encapsulated thermogels where hepatogenic growth factors were supplied from the medium (protocol MGF), and TMSC-encapsulated thermogels where hepatogenic growth factors were coencapsulated with TMSCs during the sol-to-gel transition (protocol GGF). The spherical morphology and size of the encapsulated cells were maintained in the M system during the 3D culture period of 28 days, whereas the cells changed their morphology and significant aggregation of cells was observed in the MGF and GGF systems. The hepatocyte-specific biomarker expressions and metabolic functions were negligible for the M system. However, hepatogenic genes of albumin, cytokeratin 18 (CK-18), and hepatocyte nuclear factor 4α (HNF 4α) were significantly expressed in both MGF and GGF systems. In addition, production of albumin and α-fetoprotein was also significantly observed in both MGF and GGF systems. The uptake of cardiogreen and low-density lipoprotein, typical metabolic functions of hepatocytes, was apparent for MGF and GGF. The above data indicate that the 3D culture system of PEG-L-PA thermogels provides cytocompatible microenvironments for hepatogenic differentiation of TMSCs. In particular, the successful results of the GGF system suggest that the PEG-L-PA thermogel can be a promising injectable tissue engineering system for liver tissue regeneration after optimizing the aqueous formulation of TMSCs, hepatogenic growth factors, and other biochemicals.
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University , Global Top 5 Research Program, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul, 120-750, Korea.
authors.forename: Seung-Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Min Hee
authors.initials: MH
authors.lastname: Park
authors.forename: Hyo Jung
authors.initials: HJ
authors.lastname: Moon
authors.forename: Jin Hye
authors.initials: JH
authors.lastname: Park
authors.forename: Du Young
authors.initials: du Y
authors.lastname: Ko
authors.forename: Byeongmoon
authors.initials: B
authors.lastname: Jeong
mesh_terms: D000293:Adolescent; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects*; D004705:Endocytosis; D005782:Gels / Q000494:pharmacology*; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects; D014066:Palatine Tonsil / Q000166:cytology*; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012996:Solutions; D013696:Temperature; D054457:Tissue Scaffolds / Q000737:chemistry*; D044366:Transition Temperature; D014867:Water / Q000737:chemistry
chemical_list: D005782:Gels; D010455:Peptides; D012333:RNA, Messenger; D012996:Solutions; D014867:Water; C019529:polyalanine; D011092:Polyethylene Glycols
keywords: 3D culture; TMSC; block copolymer; hepatogenesis; thermogel