The present invention relates to a method of synthesis and the use of foamed, cross-linked polyurethane polymers, as a three-dimensional support called a “scaffold” for cell cultures in vitro and for in vivo implantation for the regeneration of connective tissues such as adipose tissue, osteochondral tissue and bone tissue. In particular, the invention relates to a method of preparing polymers or foamed polyurethane co polymers, having improved hydrophilia, which involves the use of two types of catalyst, one for the cross-linking reaction and one for the foaming reaction and the use of at least one polar aprotic high-boiling solvent. Said method comprises the following steps in sequence: a) providing a solution of a polyol or a mixture of polyols in a solvent or mixture of solvents; b) heating the solution in step a) to a temperature higher than the softening temperature of the polymer precursors; c) optionally adding an organic or inorganic filler material; d) adding to the mixture in step c) an aliphatic poly-isocyanate or a mixture of poly-aliphatic isocyanates; e) adding to the mixture in step (d)) a porogenic additive; f) adding to the mixture in step e) simultaneously a cross-linking catalyst of polyols with poly-isocyanates and a foaming catalyst to form a foamed polyurethane polymer or co-polymer; g) isolating the foamed polyurethane polymer or co-polymer produced in step f).