On-chip characterization of cryoprotective agent mixtures using an EWOD-based digital microfluidic device

Area of Science:

• Biomaterials Science
• Cell Biology
• Microfluidics

Background:

• Cryopreservation is vital for tissue engineering and regenerative medicine, requiring specific cryoprotective agents (CPAs) and freeze/thaw (F/T) protocols.
• Existing CPA and F/T protocols are often difficult to adapt across different cell and tissue types.
• Efficient screening of CPA mixtures is a major challenge for developing cell-type specific cryopreservation strategies.

Purpose of the Study:

• To develop and validate an electro-wetting-on-dielectric (EWOD) based digital microfluidic platform for the cell-type specific characterization and screening of CPA mixtures.
• To demonstrate the platform's feasibility by optimizing a dimethyl sulfoxide (DMSO) and PBS mixture for a human breast cancer cell line.

Main Methods:

• An EWOD digital microfluidic platform was engineered to create and manipulate droplets of CPA mixtures.
• The platform generated an array of DMSO-PBS mixtures to map their phase change diagram.
• Cell suspensions were loaded onto the platform for on-chip screening of CPA mixture toxicity and cryoprotection.

Main Results:

• The EWOD platform successfully multiplexed DMSO and PBS droplets to form various mixtures.
• The phase change diagram of the DMSO-PBS mixture was mapped using the microfluidic system.
• On-chip screening demonstrated the platform's capability to assess CPA mixture toxicity and cryoprotective efficacy for a specific cell line.

Conclusions:

• The developed EWOD platform offers a powerful tool for the rapid, cell-type specific optimization of CPA mixtures and F/T protocols.
• This technology has the potential to significantly advance cryopreservation strategies in tissue engineering and regenerative medicine.
• Further research is needed to explore the platform's capabilities and limitations with a wider range of cell types and CPA formulations.