BME MS Defense: Siddarth Chandrasekaran

In vitro Propagation of Melanospheres Using Polydimethylsiloxane (PDMS) Showing Increased Expression of Stem-Cell Markers and Higher Clonogenic Potential

Supervised by Professor Lisa Delouise

Malignant melanomas are highly invasive tumors that are resistant to conventional treatment strategies. They are known to metastasize and extravasate into the secondary site and successfully proliferate. The biological properties of constituent cell sub-populations in melanoma are poorly characterized which makes melanomas difficult to treat. Melanoma tumors are believed to be heterogeneous with cells exhibiting phenotypic plasticity. Contrary to the belief of linear tumor progression for melanoma metastasis, where a mature melanocyte undergoes progressive mutation in its genome ultimately leading to metastatic melanoma, the notion that melanoma progression is driven by a sub-population of cells capable of self-renewal and differentiation (Cancer Stem Cells) has gained considerable attention. To this end, several approaches have been developed to isolate the sub-population of cells with tumor-initiating properties. In context of melanoma, the in vitro spheroid cell culture technique is believed to hold cues on tumor-initiation.

This work discusses an in vitro method using polydimethylsiloxane (PDMS) for propagating melanoma cells as 3D spheroids and investigates their phenotype providing further characterization of spheroid cells using microbubbles formed in PDMS to determine their clonogenic potential. Microbubbles are spherical cavities formed in PDMS about 160 µm in diameter with 60 µm circular openings. Important observations have been made on melanoma cells propagating as 3D spheroids such as increased expression of stem-cell makers and higher clonogenic potential suggesting potential tumor-initiating properties in cells propagating as 3D spheroids.