a scar inhibitory factor protein isolate from mammalian basement membranes is provided that inhibits lineage commitment and differentiation of stem cells in vitro and in vivo . the protein isolate is characterized by its ability to inhibit stem cell commitment to a fibroblastic - scar phenotype without killing the cells , thus allowing their differentiation into normal tissue phenotypes . sif thus limits the amount of scar tissue formation at the site of delivery , while maximizing the potential for the stem cells to differentiate into other tissue phenotypes . therefore , it is useful in treating numerous disorders and injuries that currently result in scar tissue or fibrous adhesion formation . the protein isolate can be administered in various modalities in vivo , i . e ., as a transdermal patch , incorporated into wound dressings , incorporated into absorbable suture material , incorporated into a bioerodible polymer matrix by itself or interspersed with differentiation factors near the site of tissue injury , sprayed onto prosthetic implants , and can be administered directly to cells cultured in vitro .