Figure 4. Regenerative potential of Ccsp⁺ BMCs.

(A) Both transtracheal (TT) and intravenous (IV) delivery of Ccsp⁺ or Ccsp^– BMCs (red) after naphthalene-induced airway injury show greater airway retention of Ccsp⁺ cells than Ccsp^– cells. Scale bars: 100 μm. Original magnification, ×20. Insets show a representative cell (scale bars: 20 μm; original magnification, ×120). (B) Of the 10⁶ cells injected, transtracheal delivery of Ccsp⁺ cells showed the most cell retention (9%) measured 4 days after cell injection. n = 4 mice per group. *P < 0.01 compared with Ccsp^– cells. (C) Ion channel genes Cftr and Enac and the tight junction protein E-cadherin were detected by real-time RT-PCR of Ccsp⁺ cells. Ccsp⁺ BMC levels of Cftr and Enac corresponded to 4% of the levels detected in airway epithelial cells, while E-cadherin levels corresponded to 8%. Low but detectable levels of Cftr (<1%) were also detected in Ccsp^– cells. n = 12 mice per group. (D) Ccsp⁺ cells coexpressed Cftr (green) and Enac (red) proteins. Hoechst counterstain was used to visualize nuclei (blue). Scale bars: 10 μm. (E) Perforated patch clamp recordings show the total conductance in Ccsp⁺ cells was larger than in Ccsp^– cells. Treating Ccsp^– cells with glybenclamide and amiloride did not change their total conductance. Application of glybenclamide did not alter the total conductance of Ccsp⁺ cells, but amiloride significantly suppressed the total conductance, suggesting that Ccsp⁺ cells express functional Enac properties. n = 5 cells per group. *P < 0.01 compared with control.