Amniotic fluid stem cell migration after intraperitoneal injection in pup rats: implication for therapy

Despite being commonly used in clinical practice, the intraperitoneal (i.p.) route has been rarely used for cell delivery. We evaluated the capacity of amniotic fluid stem (AFS) cells, administered i.p., to diffuse systemically and to integrate into tissues of healthy newborn rats. AFS cells were obtained from pregnant GFP + Sprague-Dawley rats by c-kit selection. Wild-type Sprague-Dawley newborn rats were divided into two groups receiving i.p.: (1) 2 x 10(6) AFS cells (n = 12); (2) of phosphate buffer saline (PBS) (n = 2) at 24 and 48 h after birth. Animals were either killed at 96 h of life, and organs collected for gfp amplification, or at 3 weeks of life and tissues isolated for green fluorescence protein (GFP) immunofluorescence. No adverse effects were observed after i.p. injection of PBS or AFS cells. Gfp was amplified in at least one organ in all rats injected with AFS cells except one (11/12). The intestine was the organ found most frequently positive (67%) followed by liver (25%), spleen (16%), heart (16%), lungs (16%), femur (8%) and brain (0%). Immunohistochemistry confirmed PCR results. In the short term, the i.p. administration of AFS cells, is a safe procedure and allows their migration, homing and integration into various organs of healthy newborn rats.