CELL-BINDING PEPTIDES CONJUGATED TO POLY(ETHYLENE GLYCOL) PROMOTE NEURAL CELL-AGGREGATION

We have developed a method for promoting cell aggregation with bifunct ional macromolecules synthesized by coupling cell-binding peptides to an inert, water-soluble polymer. The peptides Arg-Gly-Asp (RGD) and Ty r-ne-Gly-Ser-Arg (YIGSR) were conjugated through their amino termini t o both ends of linear poly(ethylene glycol) (PEG), producing bifunctio nal hybrid polymers: RGD-PEG-RGD and YIGSR-PEG-YIGSR. RGD-PEG-RGD prom oted aggregation of mechanically-dissociated fetal brain cells, pheoch romocytoma cells (PC12), and neuroblastoma cells maintained in rotatio n culture at 37 degrees C. Enhanced aggregation was noticeable within 10 minutes and became more pronounced over the next several hours: aft er 7-9 hours, the mean aggregate volume was up to 10 times larger than the mean volume produced in suspensions containing unmodified PEG. Si milar results were obtained with YIGSR-PEG-YIGSR and PC12 cells. Enhan cement in aggregation correlated with the ability of soluble RGD or YI GSR to inhibit cell adhesion to surfaces coated with laminin or fibron ectin. This method for promoting aggregation may be useful for large s cale culture of anchorage dependent cells, eliminating the need for mi crocarriers. In addition, aggregates formed by this method may be suit able for use in artificial organs or as cell transplants for tissue re generation.