Prolactin supplementation to culture medium improves beta-cell survival

OBJECTIVES.: Recent studies demonstrated that prolactin (PRL) has beneficial effects on β cells for islet transplantation. We examined the effect of human recombinant PRL (rhPRL) supplementation to the culture media to determine its potential use in the context of clinical islet transplantation. MATERIALS AND METHODS.: Each human islet isolated from 14 deceased multiorgan donors was cultured in Miami modified media-1 supplemented with or without rhPRL (500 μg/L) for 48 hr. β-Cell survival and proliferation (BrdU and Ki-67) were determined by laser scanning cytometry. The cytoprotective effects of rhPRL against noxious stimuli were assessed by flow cytometry (tetramethylrhodamine ethyl ester). Cytokine/chemokine and tissue factor productions were measured in vitro, and islet potency was assessed in vivo in diabetic immunodeficient mice. RESULTS.: β-Cell survival during culture was 37% higher in the rhPRL group than in control (P=0.029). rhPRL protected β cells in vitro from cytokines, Nitric oxide donor, and H2O 2. The exposure to rhPRL did not affect human β-cell proliferation with our protocol. rhPRL treatment did not alter cytokine/chemokine and tissue factor production in vitro or affected human islet functionality in vivo: recipient mice achieved normoglycemia with a comparable tempo, whereas loss of graft function was observed in two of the seven mice in the control group and in none of the rhPRL group (p=n.s.). CONCLUSION.: rhPRL supplementation to islet culture media improved human β-cell-specific survival without altering islet quality. Addition of rhPRL to cultured islets may grant a more viable β-cell mass in culture. The development of β-cell cytoprotective strategies will be of assistance in improving islet transplantation outcomes.