Growth of Human Mesenchymal Stem Cells (MSCs) on Films of Enzymatically Modified Chitosan Abdulhadi Aljawish and Lionel Muniglia Universit e De Lorraine, Laboratoire D’ing enierie Des Biomol ecules (LIBio), TSA40602-F-54518, Vandœuvre-le `s-Nancy, France Isabelle Chevalot Universit e De Lorraine, Laboratoire R eactions Et G enie Des Proc ed es (LRGP-CNRS-UMR 7274), TSA40602-F-54518 Vandœuvre-le `s-Nancy, France DOI 10.1002/btpr.2216 Published online February 4, 2016 in Wiley Online Library (wileyonlinelibrary.com) Mesenchymal stem cells (MSCs) are known to be an attractive cell source for tissue engi- neering and regenerative medicine. One of the main limiting steps for clinical use or bio- technological purposes is the expansion step. The research of compatible biomaterials for MSCs expansion is recently regarded as an attractive topic. The aim of this study was to create new functional biomaterial for MSCs expansion by evaluating the impact of chitosan derivative films modified by enzymatic approach. First, chitosan particles were enzymatically modified with ferulic acid (FA) or ethyl ferulate (EF) under an eco-friendly procedure. Then, films of chitosan and its modified derivatives were prepared and evaluated by physico- chemical and biological properties. Results showed that the enzymatic grafting of FA or EF onto chitosan significantly increased hydrophobic and antioxidant properties of chitosan films. The MSCs cell viability on chitosan derivative films also increased depending on the film thickness and the quantity of grafted phenols. Furthermore, the cytotoxicity test showed the absence of toxic effect of chitosan derivative films towards MSCs cells. Cell morphology showed a well attached and spread phenotype of MSCs cells on chitosan derivative films. On the other hand, due to the higher phenol content of FA-chitosan films, their hydrophobic, antioxidant properties and cell adhesion were improved in comparison with those of EF- chitosan films. Finally, this enzymatic process can be considered as a promising process to favor MSCs cell growth as well as to create useful biomaterials for biomedical applications especially for tissue engineering. V C 2016 American Institute of Chemical Engineers Biotech- nol. Prog., 32:491–500, 2016 Keywords: enzymatic modification, chitosan films, ABTS, cell adhesion, mesenchymal stem cells Introduction Mesenchymal stem cells (MSCs) isolated from bone mar- row have been used as an attractive cell source for tissue engineering and regenerative medicine. 1–3 MSCs are self- renewable adult stem cells with great therapeutic potential due to their differentiation into multiple tissue-specific line- ages such as osteoblasts, chondrocytes and adipocytes. 4 However, one of the main limiting steps for clinical use or biotechnological purposes is the expansion step, as MSCs are present in small amount in adult tissues. 5 MSCs are clas- sically expanded in small-scale culture systems (T-flasks). This culture system presents many drawbacks, such as poor scale-up ability, contamination risks from frequent cell pas- saging and a lack of pH and oxygen control. 6 Tissue engi- neering and cell therapy require large quantities of cells that cannot be easily achieved using processes in static flasks. 7 Consequently, new techniques have emerged for MSC expansion, especially with cells attached on microcarriers in stirred bioreactors. 8–10 The main advantage of microcarrier-based culture is the high ratio of adhesion surface to medium volume, enabling the attainment of high cell densities. This culture system showed some drawbacks such as cell aggregation during expansion. To avoid cell aggregation, some studies proposed controlling operating parameters such as agitation rate, cell density, and addition of carriers. 6,11 Sometimes, due to the smooth surface of microcarriers such as glass microcarriers and Cytodex, MSCs cannot attach firmly and may detach and be washed away during medium changes. 12 In addition, those microcarriers cannot be digested in the human body. 13 consequently, microcarriers prepared by degradable materials in the human body exhibiting heterogeneous surface such as gelatin, chitosan in the human body are recently regarded as an attractive alternative of nondegradable microcarriers with smooth surface. 13–20 Among the degradable materials that can be used to pre- pare the microcarriers for cell growth, chitosan, the deacety- lated derivative of chitin, is a copolymer of glucosamine and Correspondence concerning this article should be addressed to I. Chevalot at isabelle.chevalot@univ-lorraine.fr. V C 2016 American Institute of Chemical Engineers 491