Cord Blood Mesenchymal Stem Cells for Acute Renal Failure Repair.

Introduction: Human cord blood (CB) represents an interesting source of mesenchymal stem cells (MSCs) with different cell “competence” and feasible clinical applications. Up to now patients affected by acute renal failure (ARF) are treated by unsuccessful pharmacological therapies and it is an interesting possibility that CB MSCs or other potential progenitor cell subpopulations could be used for therapeutic purpose in renal repair. Aim of this study was to isolate and culture MSCs from full-term UCB and to test their ability to promote renal repair when transplanted into NOD-SCID mice with acute renal failure.

Methods: MSCs were isolated with a lineage-depletion negative immuno-selection procedure (Rosette Sep, StemCell Technologies, Vancouver, Canada) from buffy coat of CB (n=17) without lysis of red blood cells. Cell suspension was seeded at 1×10⁶ cells/cm², in 35mm/tissue culture dish in the presence of αMEM, 20 % FBS, 2mM L-Glutamine and Penicillin/Streptomycin. Immunophenotype was evaluated by flow cytometric analysis while the differentiation assays were performed towards adipogenic, osteogenic and chondrogenic lineages in order to confirm their mesenchymal features.

To induce acute renal failure, NOD-SCID mice (n=10) were injected with cisplatin (12.7 mg/KG s.c.). This drug is associated with renal function deterioration, measured as serum blood urea nitrogen (BUN), peaking at day 4–5. After one day the mice received i.v. saline or 5×10⁵ CB MSCs. Renal function and histology were evaluated.

Results: The success rate of isolating MSCs from CB units was 17.6%. Flow cytometric analysis showed that MSCs were positive for CD44 (69%), CD105 (26%), CD90 (99%), HLA class I (80%) and negative for CD31, CD45, CD34, HLA class II. Moreover, within the CB MSCs we identified a subpopulation (37.5%) characterized by CD146+/34−/45− and consistent with perivascular/pericyte-like cells. Moreover we demonstrated and confirmed that CB MSCs were capable to differentiate in osteogenic and condrogenic but not adipogenic lineages, as recently shown also by other groups. In vitro differentiation towards epithelial lineage is in progress.

In vivo results showed that CB MSCs significantly protected cisplatin-treated mice from renal function impairment at day 4 (BUN: cisplatin+saline 115±5 vs cisplatin+CB MSCs 64±13 mg/dl, p<0.01). Kidneys of mice at 4 days after cisplatin injection were examined histologically and assigned scores (0 to 3) for tubular cell degeneration changes, hyaline casts and cell lysis. Mice receiving CB MSCs exhibited lower degree of tubular injury compared to mice given saline (average score: CB MSCs 0.5, range from 0.3 to 1 vs cisplatin + saline, 1, range 0.7 to 1.3, p<0.047).

Conclusion: These preliminary results indicate that human CB MSCs exhibit reparative potential in acute renal failure. More evidences demonstrating the plasticity of CB stem cells will provide an exciting opportunity to explore the use of this stem cell source in regenerative medicine for patients with renal disease.