Biomedical and tissue engineering devices, such as surgical sutures and microporous scaffolds, respectively, which undergo swelling and increase in dimensions when placed in aqueous environments such as living tissues, are produced by the melt-spinning or electrostatic spinning into strong monofilament and multifilament yarns or microfibrous fabrics, respectively. Such devices are formed from especially high molecular weight crystalline polyether-esters having a minimum inherent viscosity of 0.8 dL/g and heat of fusion of at least 5 J/g, wherein the polyether-esters are made by grafting to a polyester component a polyether glycol component having a minimum molecular weight of about 11 kDa with at least one cyclic monomer.