Raman spectroscopy enables noninvasive biochemical identification of the collagen regeneration in cutaneous wound healing of diabetic mice treated with MSCs.

Mesenchymal stem cells (MSCs) had been reported as a novel therapeutic strategy for non-healing diabetic cutaneous wound mainly by promoting the formation of extracellular matrix (ECM) and neovasculature. Collagen regeneration is one of the key processes of ECM remodeling in wound healing. Accordingly, rapid assessment of the collagen content in a noninvasive manner can promptly provide objective evaluation for MSC therapy of cutaneous wound healing and strength evidence to adjust therapeutic regimen. In the present study, noninvasive Raman microspectroscopy was used for tracing the regeneration status of collagen during diabetic wound healing with MSCs. Wound tissues of normal mice, diabetic mice, and MSC-treated diabetic mice were subjected to Masson trichrome staining assay and submitted to spectroscopic analysis by Raman microspectroscopy after wounding 7, 14, and 21 days. Masson trichrome staining demonstrated that there was more collagen deposition in diabetic + MSCs group relative to diabetic group. The relative intensity of Raman collagen peak positions at 937, 1004, 1321, 1452, and 1662 cm-1 increased in MSC-treated diabetic group compared to diabetic group, although normal mice group had the highest relative intensity of collagen peak bands. Correlation analysis suggested that the spectral bands had a high positive correlation with the collagen intensity detected by Masson trichrome staining in wound tissues of three groups. Our results demonstrate that Raman microspectroscopy has potential application in rapidly and quantitatively assessing diabetic wound healing with MSCs by monitoring collagen variation, which may provide a novel method for the study of skin regeneration.