A. V. Gore1, L. E. Bible1, K. J. Song1, A. M. Mohr1, D. H. Livingston1, Z. C. Sifri1 1Rutgers New Jersey Medical School,Surgery,Newark, NJ, USA
Introduction: Rat lungs undergo full histologic recovery one week following unilateral lung contusion (LC). This healing is impaired when LC is followed by hemorrhagic shock (HS), and even more so in the setting of chronic stress (CS). We hypothesize that injecting mesenchymal stem cells (MSC) could reverse LCHS/CS impaired lung healing.
Methods: Male Sprague-Dawley (SD) rats (n=5-6/group) underwent LCHS/CS with or without the addition of a single iv dose of 5 x 106 SD rat MSCs at the time of resuscitation. Rats experienced two hours of restraint stress on days 1-6 following injury and were sacrificed on day 7. Lung histology was scored according to a well-established lung injury score (LIS) to grade injury. Components of the LIS include interstitial and pulmonary edema, alveolar integrity, and inflammatory cells/high power field (hpf) averaged over 30 fields. Total scores range from 0-11. Data expressed as mean ± SD; analyzed by ANOVA followed by Tukey’s multiple comparison test.
Results: Seven days following insolated LC, LIS has returned to 0.8 ± 0.4, while it remains elevated with the addition of HS (3.7 ± 0.8) and further elevated with combined LCHS/CS (7.2 ± 2.2), as previously reported. Addition of MSC to LCHS/CS decreased LIS to 2.0 ± 1.3 and decreased all subgroup scores (inflammatory cells, interstitial and pulmonary edema, and alveolar integrity) significantly as compared to LCHS/CS.
Conclusion: In this rat lung contusion model, the severe impairment of lung healing seen seven days following LCHS/CS is reversed by MSCs given early at the time of resuscitation. This improvement in healing is associated with a decrease in the number of inflammatory cells and decreases in lung edema scores. Further study into timing of administration and mechanisms by which MSC improve wound healing is warranted.
