5. Conclusion
A simple and cost-effective method for the generation of tumor spheroids has been reported. It consists of enveloping individual tumor cells in agarose hydrogels (with 0.25 or 0.125% weight percentage) blended with 0.02% collagen, where agarose reproduces the biomechanical features of the ECM, while collagen provides the anchoring sites for the membrane proteins. The growth of tumoroids deriving from three breast cancer cells lines was analyzed and compared. Interestingly, one cell line, MDA-MB-231 did not form spheroids in any of the conditions employed, while the other two lines, MCF-7 and MDA-MD-361displayed a quite similar behavior.
The variation of the agarose amount affected the physical and mechanical features of the resulting hydrogel and the growth of spheroids. Indeed the stiffer the hydrogel, more compact and slightly smaller the tumoroids resulted. Therefore, depending on the type of tumoroids to be prepared and studied, the hydrogel composition can be easily tuned. The growth of the spheroids was monitored up to 2 weeks, and the qualitative analysis of their viability evidenced few dead cells only after 14 days.
Preliminary drug testing studies with cisplatin show that the blended hydrogels allow following the response of the spheroids to the drug administration. This aspect makes the system potentially useful for routine drug screening.
Finally, the degradability of the hydrogels upon enzymatic treatment was demonstrated, leading to complete recovery of tumoroids in the case of the softest hydrogels, while to a partial recovery in the hydrogel with 0.25% agarose. The possibility to recover the spheroids is of a paramount importance as it enables further biomolecular studies with the collected samples.