Poster Z5 - Lipoaspirate Preparation Platform Enables Automated Washing and Integrated Mechanical Processing for Downstream Fat Grafting

Introduction: Autologous fat grafting of human lipoaspirate (LA) has emerged as a state-of-the-art technique for both cosmetic surgery and regenerative medicine. Given that adipose tissue is the largest source of stem cells in the body and its relative ease of harvest, LA has emerged as the future for regenerative stem cell therapeutics. Preparation of LA requires multiple rounds of washing with saline before reinjection back into the patient. Historically, this process has been performed manually, oftentimes with kitchen strainers and Erlenmeyer flasks for decantation. Although some commercialized processing devices exist (i.e., REVOLVE, Puregraft), many surgeons still prefer to manually wash the lipoaspirate themselves. Given the lack of standardization between these processing methodologies, graft take is highly variable, ranging from 20-80%. We hypothesize that a new closed-loop fluidic preparation platform could be automated using peristaltic pumps to both enhance the washing of LA and integrate mechanical processing for injectable graft production, resulting in minimal adipose tissue manipulation and standardization within the operating room.

Materials and

Methods: The Preparation Device (PD) was designed and manufactured using stereolithography to enable closed-loop LA washing using peristaltic pumps. Using human LA samples, the PD was optimized first with a batch and then a dynamic wash protocol and was compared to a traditional washing approach. Resultant washed LA samples underwent a visual colorimetric comparison. Additionally, LA samples were mechanically processed using our lab’s Emulsification and Micronization Device (EMD) for downstream stem/progenitor cell analysis. All samples were enzymatically digested for ex vivo measurement of cell counts and cell viability. Stem/progenitor markers included Mesenchymal Stem Cells (MSCs), Endothelial Progenitor Cells (EPCs), and Pericytes. Pneumatic pinch valve banks were manufactured to enable automated processing throughout the fluidic platform.

Results, Conclusions, and Discussions: Both batch and dynamic wash protocols produced LA with equivalent color and quality as traditional manual washing. Batch washing using a simple dual-inlet cap enabled mixing of LA and saline. Internal baffles within the PD helped increase agitation within the PD’s internal cavity. An updated cap with three separate saline jets, a fat inlet, and a vent enhanced mixing within the PD. Utilizing a dynamic wash protocol, the three saline jets created rotational mixing counterclockwise to the internal baffles, maintain LA within the PD body during washing. Dynamic washing significantly decreased wash times. Neither wash protocols significantly affected cell counts or viability. Both MSC and EPC populations rose from using the PD. Combining the EMD within the PD platform enabled closed-loop mechanical processing and significantly improved EPC numbers (5-fold) compared to manual washed/syringe pump-driven EMD processing. Pneumatic pinch valves enabled automation of the platform, resulting in decreased wash time and minimal tissue manipulation.

Our new fluidic platform demonstrates effective washing of LA within a closed-loop system and demonstrates minimal manipulation and purity of final adipose tissue. Additionally, this platform enables the simple integration of mechanical processing while enriching for EPCs. Automation of this platform will enable improved reproducibility within clinical settings and save time within the operating room. Future directions will explore fat graft retention within an in vivo murine model and explore further optimization of wash protocols not possible prior to automation.

Acknowledgements (Optional): The authors would like to thank Dr. Siamak Agha, Dr. Keyianoosh Paydar, Dr. Garrett Wirth, Dr. Joseph T. Cruise, and Cristela Mejia for their support and assistance with specimen collection.