(557) Identifying the Ideal Mesenchymal Stem Cell Phenotype for Treating Cystic Fibrosis Lung Infection and Inflammation

Background: Modulator therapy and advanced clinical care has improved the quality of life and extended life expectancy for individuals with cystic fibrosis (CF). Since not all CF patients benefit from modulator therapy and established disease continues to provide challenges for CF patient care, innovation in treating infection and inflammation are still required. Human mesenchymal stem cells (hMSCs) have been proven to be safe ( >1000 clinical trials globally), including our recently completed Phase I "First in CF" clinical trial. Utilization of hMSCs to treat inflammation in the context of infection has been a worldwide pursuit however, some patients have sub-optimal response. To improve outcomes in future hMSC CF clinical trials, we have pursued the characterization of the optimal hMSC molecular and functional donor phenotype that would be ideal to treat the complexity of infection and inflammation in CF. Our hypothesis is that a specific hMSC molecular and function fingerprint will correlate with optimal potency.

Methods: Bone marrow derived hMSCs (n=12) were obtained and cultured using standardized conditions. Antibiotic free conditioned medium from the hMSCs (72 hours) with and without exposure to bacteria, were screened for antimicrobial potency against: Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae, Mycobacteria avium, Mycobacteria intracellulare, Mycobacteria abscessus and Burkhoderia cepacia colony forming units (cfus) and growth by optical density (OD). hMSCs transcriptional response to pathogens was monitored using RT-PCR focusing on: LL-37, IL-6, heme oxygenase I and CCL20. hMSC secreted products were monitored using Luminex technology. hMSC anti-inflammatory potency was quantified using in vitro healthy control and CF cell targets (macrophages, airway epithelial cells and gastrointestinal epithelial cells) stimulated with either free bacteria or bacterial analogs. Selected donor hMSCs were also screened for in vivo antimicrobial and anti-inflammatory potency utilizing the murine model of CF lung infection induced inflammation.

Results: hMSCs donor uniqueness demonstrated diversity in antimicrobial and anti-inflammatory potency. hMSC donor expression of LL-37, IL-6 and heme oxygenase 1, CCL20 and functional potency against specific pathogens was donor source specific. hMSC functional anti-inflammatory activity also correlated to unique hMSC molecular fingerprints. LL-37 and IL-6 dominance was associated with Pseudomonas aeruginosa infections and inflammation resolution, whereas heme oxygenase 1 and CCL20 correlated with non-tuberculous mycobacterium infection and inflammation resolution. Preliminary studies suggest that there is overlap with hMSC analytes and infection induced inflammation resolution, suggesting that disease specific hMSC donor selection is likely to provide the best product for future clinical trials.


Conclusions: hMSCs should be screened for disease and pathogen specific potency to optimize potential clinical efficacy. Defining a CF disease specific hMSC product will enhance therapeutic outcomes, improving the potential for clinical efficacy in CF. In addition, understanding hMSC responsiveness to well characterized environments will provide unique directions in therapeutic development.

Acknowledgements: This work was graciously supported by the Cystic Fibrosis Foundation, The Marcus Foundation and the David and Virginia Baldwin Fund.

References: