Effects of poly-L-lysine and collagen on FH-B-TPN cell differentiation into endocrine cell phenotype

Pdx-1 genetically engineered FH-B-TPN cells might represent a source for insulin-secreting cells. We then have tested whether poly-L-lysine (PLL) and collagen (C) exposure in vitro promote three-dimensional particle formation and differentiation toward an endocrine cell phenotype. On these matrices, we observed that FH-B-TPN cells showed a tendency to either aggregate when seeded on PLL or to form uniform cell monolayers, but not to aggregate on C. While insulin was released in any condition, GSIR was only associated with PLL mainly at 24 and 72 hours of culture. Various culture matrices influenced the expression of glucose transporter type 2 and gluco kinase, being they expressed more intensively on PLL rather than C or in controls. mRNA expression for NeuroD/Beta2, Isl-1, Ras, Metalloproteinase-2 (MMP-2), -9 and -7 also were affected, with PLL inducing increased expression of NeuroD/Beta2 of Isl-1, and no difference between C and control. PLL, unlike C, strongly increased Ras through observation times. MPP-2 and -9 were decreased by both PLL and C, whereas MMP-7 was increased by PLL. PLL, usually employed to promote culture cell adhesion, has been proven capable to stimulate pancreatic endocrine function and cell aggregation and to stimulate gene expression of key markers for either insulin transcription or MMP-7.