691. CFTR mRNA is expressed in lungs of CFTR-KO mice following administration of adult marrow cells from wild-type donor mice

Top of pageAbstract A novel approach for treatment of cystic fibrosis and other lung diseases is suggested by recent studies demonstrating that airway and alveolar epithelium in adult mice can be repopulated with cells derived from bone marrow of adult donor mice. The mechanisms by which marrow-derived cells transform into epithelial cells are unknown. However pre-existing lung injury increases localization of bone marrow cells to lung epithelium suggesting that active repair or remodeling of lung epithelium may create a more conducive environment for bone marrow cells to lodge and transform into epithelial cells. We have previously demonstrated that donor-marrow-derived cells could localize to lungs of CFTR KO mice and that different experimentally-induced injury patterns could influence the distribution of the recruited marrow cells in the recipient lungs. We now demonstrate that wildtype CFTR mRNA is expressed in CFTR-KO lungs following administration of donor marrow cells from animals containing wtCFTR. Adult female CFTR-KO mice aged 6-12 weeks received intraperitoneal administration of naphthalene (275 mg/kg body weight of a stock solution of 10 ml/kg in sterile soybean oil) to induce airway lung epithelial injury. 3-4 days later, at the time of peak lung injury, treated and naive control CFTR KO mice received tail vein injection of 1 × 106 stromal marrow cells originally obtained from transgenic constitutive GFP-expressing donors (C57Bl/6 background) and cultured for 10 days prior to use. Mice were euthanized 1 week and 3 months after donor marrow cell administration and the lungs flash frozen in liquid N2, homogenized, and RNA extracted with Trizol. DNAse-treated purified RNA was reverse transcribed followed by PCR amplification using specific primers for murine CFTR (mCF11/mCF12). wtCFTR was observed in naphthalene-injured CFTR-KO mouse lungs collected 3 months but not 1 week after donor marrow administration. No wtCFTR expression was detected in un-injured transplanted CFTR-KO mice at either time point. Importantly, wtCFTR mRNA expression was not detected in donor marrow cells or in mature circulating leukocytes. These results suggest that donor marrow cells that traffic to lung subsequently express wtCFTR as they acquire an epithelial cell phenotype. Lung injury appears to increase this process. Importantly, these results suggest that marrow cells can directly traffic to lung and express a specific lung epithelial protein. Engraftment of the recipient marrow may not be necessary.