Detection of the differentiation state of salivary gland organoids for tissue engineering by Raman spectroscopy

Repair or reconstruction of organs is the goal of regenerative medicine. Bioengineered organoids that can differentiate when implanted in-vivo to partially restore organ function are being developed. Potentially, such organoids can be used to treat many medical conditions. A non-invasive method for quality monitoring of tissue engineered constructs is needed in order to ensure that they are ready for implantation. Raman micro-spectroscopy offers a way to quantitatively analyze cells and tissues without sample preparation or labelling dyes, which are not allowed in constructs used for the human implantation. Epithelial progenitor cells are parts of the complex organoids derived from the embryonic salivary gland cells. We have collected Raman spectra of the epithelial (acinar and ductal) cells treated with Fibroblast Growth Factor 2 (FGF2) and grown in organoids ex vivo over a period of (1 - 7 days). Evolution of the organoids over time was detected with Raman. These modifications, corresponding to the C-C stretch and C-H bend in proteins, as well as alterations in the Amide I and III envelopes, likely may correlate with changes in the cell environment or their differentiation state. Our goal is to develop Raman metrics that can be applied to the non-invasive monitoring of organoids.