Development of a Closed Fluidic System with Single-Use Cartridge for Automated Isolation of Stromal Vascular Fraction from Adipose Tissue

Isolation of stromal vascular fraction (SVF) from adipose tissue is typically performed manually with multiple separate steps, different vessels and final centrifugation. The process is therefore time-consuming, operator-dependent and exposed to the risk of contamination.

The diploma thesis addresses the development of a closed fluidic system with a single-use cartridge that converts the manual procedure into an automated process and adapts it to the limitations of the existing device.

Problem

Isolation of stromal vascular fraction (SVF) from adipose tissue is typically performed manually with multiple separate steps, different vessels and final centrifugation. The process is therefore time-consuming, operator-dependent and exposed to the risk of contamination.

The diploma thesis addresses the development of a closed fluidic system with a single-use cartridge that converts the manual procedure into an automated process and adapts it to the limitations of the existing device.

Solution and Method

The transition from a syringe-based design to a system with bags and peristaltic pumps and the design development of the cartridge are presented. The choices of materials, tubing, connectors, manifolds, pumps, heating assembly and hollow fibre module are justified.

The process steps from pre-filling and enzymatic treatment to decanting, concentration and obtaining the final product are described.

Using an orientation assessment of fluid mechanics (Reynolds and cavitation number, pressure drop and wall shear stress), the flow regime, shear loads on cells, influence of geometry and risk of blockages were evaluated.

Theoretical findings were compared with the results of 63 experiments conducted between 2023 and 2026, which included testing of pumps, tubing dimensions, mixing, sealing, concentration and comparison with centrifugation.

Results

The analysis showed laminar flow and a large safety margin regarding cavitation, whilst the estimated shear loads remained below the range where, according to the literature, deterioration of viability would be expected.

Pump speed itself did not harm the cells even at the highest tested values, whilst the method of transfer had a significant effect on yield; mixing with pauses was more effective than continuous pumping. Compared with centrifugation, viability was comparable or slightly better, whilst lower yield was primarily associated with decanting and filtration.

The final design supports cycles for 40, 100 and 120 mL of lipoaspirate, whilst the final product volume remains approximately between 6 and 9.5 mL. In more mature versions, viability consistently exceeded 80%. Six of the seven hypotheses were confirmed, one indirectly and one partially. The main remaining limitation is the concentration yield, which represents an important starting point for further development.