In a recent article in Scientific Reports, researchers examined the use of single-layer graphene oxide (slGO) nanosheets to enhance the proliferation and osteogenic differentiation of human bone marrow stem cells (hBMSCs) when encapsulated in alginate microgels. Integrating slGO into a microfluidic system aims to create a conducive three-dimensional (3D) environment that mimics natural tissue conditions, thereby promoting cell growth and functionality.
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Background
Graphene oxide has become prominent in biomedical applications due to its high surface area, mechanical strength, and biocompatibility. Previous studies suggest that graphene oxide’s size and surface properties significantly influence stem cell behavior, especially in promoting differentiation into osteoblasts. Controlling these properties enables tailored applications in regenerative medicine.
Microfluidic cell encapsulation offers advantages like precise droplet control, which is essential for cell viability and nutrient exchange. This study expands on existing knowledge by investigating the combined effects of slGO and alginate microgels on hBMSCs to improve osteogenic potential.
The Current Study
The researchers employed various techniques to characterize slGO and analyze its effects on hBMSCs. Fourier transform infrared (FTIR) spectroscopy was utilized to identify functional groups in slGO, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to examine the surface morphology and topography of the nanosheets. The size distribution and zeta potential of slGO were measured using a Zetasizer Nano ZS95, ensuring that the nanosheets were within the optimal size range for biological applications.
To evaluate the cytotoxicity of slGO, an MTT assay was performed on hBMSCs exposed to varying concentrations of slGO over different time periods. The metabolic activity of the cells was quantified to determine the impact of slGO on cell viability. Additionally, the encapsulation of hBMSCs in alginate microgels was achieved using a microfluidic device, which facilitated the generation of uniform droplets.
The encapsulated cells were subjected to live/dead assays to assess their viability over time. Furthermore, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was conducted to analyze the expression levels of osteogenic marker genes, including Runx2, alkaline phosphatase (ALP), and osteocalcin (OCN), providing insights into the differentiation status of the hBMSCs.
Results and Discussion
The slGO nanosheets exhibited a size of approximately 916.9 nm after sonication, which was favorable for stem cell differentiation. The zeta potential of -18.7 mV indicated good stability of the slGO suspension.
MTT assay results showed that low slGO concentrations (0.002 to 0.2 μg/mL) did not significantly affect cell viability, while higher concentrations (2 and 20 μg/mL) led to a notable decrease in hBMSC proliferation after 48 hours. This suggests that slGO is biocompatible at low doses but can become cytotoxic at higher levels, consistent with prior studies on nanomaterial dosage effects.
Encapsulation of hBMSCs in alginate microgels supported cell survival and proliferation, as shown by live/dead assays indicating high viability. qRT-PCR analysis revealed significantly increased expression of osteogenic markers in slGO-encapsulated hBMSCs compared to controls, with enhanced levels of Runx2, ALP, and OCN. These findings indicate that slGO not only supports cell viability but also promotes osteogenic differentiation. These findings indicate slGO’s potential as a bioactive component in bone tissue engineering scaffolds, enhancing both cell survival and differentiation.
The study also emphasizes the importance of microfluidics in achieving uniform cell encapsulation, crucial for consistent cell responses. Integrating slGO into alginate microgels within a microfluidic system offers an innovative approach to developing biomaterials for regenerative medicine. This method allows for fine-tuning microgel properties through slGO incorporation, presenting opportunities for optimized stem cell therapies.
Conclusion
This study demonstrates that slGO nanosheets can enhance the proliferation and osteogenic differentiation of hBMSCs when encapsulated in alginate microgels. The results support slGO’s biocompatibility at low concentrations and its potential role as a bioactive component in tissue engineering. The microfluidic encapsulation method further refines this approach, enabling precise control over the cellular microenvironment.
These findings contribute to the growing understanding of nanomaterials in regenerative medicine and highlight slGO’s potential as a candidate for advanced scaffolds supporting stem cell function and tissue regeneration. Future research should focus on optimizing formulations and assessing long-term in vivo effects to fully realize slGO’s therapeutic potential.
Journal Reference
Soleymani H., et al. (2024). Single-layer graphene oxide nanosheets induce proliferation and Osteogenesis of single-cell hBMSCs encapsulated in Alginate Microgels. Scientific Reports 14, 25272. DOI: 10.1038/s41598-024-76957-y, https://www.nature.com/articles/s41598-024-76957-y