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Patent of the Week – More on Cell Release; Ultrasonic Cavitation
The patent world certainly mirrors the scientific effort to explore methods of cell release and dissociation without the use of potentially damaging enzymes. In this week’s “Patent of the Week,” a group from New York has patented a new method of using ultrasonic cavitation to separate adipose cells. Noting the utility of collagenase, they also note that the use of this enzyme may be disadvantageous for cellular products that are to be used in humans. For uses such as tissue reconstruction or regeneration, e.g., breast reconstruction procedures, cosmetic skin rejuvenation or usage in cosmetic tissue fillers that are used during plastic surgery; the FDA may consider collagenase use to result in a “maximally manipulated” cellular product. This would potentially place stromal or mesenchymal vascular cells derived from adipose tissue in a category that requires drug approval, even if the cell fraction is to be used cosmetically and not clinically.
Adipose tissue containing blood vessels is removed from a subject and a probe of a commercially available ultrasonic cavitation device is placed into contact with the adipose tissue. In most cases, about 5 minutes to 1 hour of ultrasonic exposure explodes or lyses most of the fat cells in the adipose tissue and releases the stromal vascular fraction containing stromal and mesenchymal stem cells, endothelial precursors and other cell types.
Following sonication, three layers form after settlement of the dissociated adipose tissue. The top layer is a free lipid layer. The middle layer includes the lattice and adipocyte aggregates. The bottom layer or cell pellet which is produced after the treated composition is allowed to settle or is centrifuged contains the stromal vascular fraction cells (SVFC’s).
After the adipose tissue containing blood vessels is treated using the ultrasonic cavitation device, the exploded fat (at the top of the composition) can be removed and the remaining stromal or mesenchymal vascular fraction purified or assayed (such as by flow cytometry) for the presence of desired cell types, including stem and endothelial precursor cells. Of course, while the vascular fraction or isolated cells derived from adipose tissue may be used directly for treatment, the cells, especially stem cells, may be significantly expanded in culture.
The long term question as to whether the sonication may damage the cells in some manner requires more validation, but there is no question that more and more investigators are searching for enzyme-free methods of cell release and dissociation.
U.S. Pat. No. 8,440,440
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