Selective lysing of cells using ultrasound

Abstract

Described are embodiments that employ ultrasonic energy to selectively lyse larger adipose cells in a suspension containing adipose cells of different sizes resulting in a suspension in which the only viable cells are the small adipose cells and stem cells. Embodiments provide for generating an acoustic standing wave field of sufficient intensity and proper geometry, that high shear stress is induced on the cell membranes of cells larger than a predetermined size. The remaining small adipose cells can be physically separated from the suspension after the suspension is subjected to the acoustic standing wave field.

Description

I. CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Patent Application Ser. No. 61 / 266,867, filed Dec. 4, 2009 entitled “SELECTIVE LYSING OF CELLS USING ULTRASOUND,” the contents of which are hereby incorporated by reference in their entirety as if set forth herein in full.II. FIELD OF THE INVENTION[0002]Embodiments of the present invention relate to methods and devices for use in the selective “lysing,” i.e., destroying, of cells using ultrasound. In particular, the embodiments relate to the selective termination of larger, generally older, adipose cells in a mixture of adipose cells of various sizes and maturities such as found in an extract from animal, e.g., human, tissues.III. BACKGROUND OF THE INVENTION[0003]When fat cells are extracted from the body, typically in a liposuction procedure, they encompass a range of sizes, from less than 25 microns in diameter, to more than 100 microns in diameter. The smaller cells are typically pre-adipocyt...

AI Technical Summary

Benefits of technology

[0014]Embodiments of the present invention employ ultrasonic energy to selectively lyse larger adipose cells in a suspension containing adipose cells of different sizes resulting in a suspension in which the only viable cells are the small adipose cells. The embodiments also provide for easily maintaining the sterility of the suspension during lysing by using a cartridge as the chamber for holding the suspension when it is being lysed. The cartridge, in some embodiments, is used only a single time, which reduces the risk of introducing contaminants into the suspension. As used herein “lysis” refers to the destruction of cells, a process that frequently involves disruption of the cell membrane. Thus, the lysed cells spill their internal lipids into the suspension. As a result, the remaining small adipose cells can be physically separated from the suspension.

[0018]The prior art attempted to have all the cells of a specific type or some acoustically differentiable characteristic in a single zone, and all the cells of a different characteristic in another zone, so that the two cell types could be easily separated by separation of the flow streams containing the different zones.

[0020]It should be also noted that unlike nearly every other cell in the body, normal, healthy adipose cells can vary in size over a wide range. This is very different from the case often described in the prior art, in which different cell types, e.g. erythrocytes and adipocytes, are to be separated. Erythrocytes, for example, all are within a very narrow size range of 6-8 micron. Because they are very small and very dense, these cells have a high acoustic contrast compared to blood serum and other cells. Thus, they can be separated relatively easily by the prior art techniques. Those same techniques would be far less effective, if at all, on typical mixtures of adipose cells.

Problems solved by technology

The more mature cells, on the other hand, do not generally express the vascular growth factors, and are more likely to undergo necrosis after re-implantation.

Filtering of the aspirate is also possible, although this can also be a time consuming process, and can also cause damage to the cells of interest as they pass through the filter material.

For example, a cluster of more than a few 50 micron diameter cells would be filtered out by a filter with a 150 micron mesh, which defeats the purpose of the entire filtering process.

Thus, neither centrifugation nor filtering has completely solved the problem of isolating smaller, younger adipose cells.

However, the stratification is imprecise; it can be affected by clustering of the cells; and it can cause damage to the desired cells by both additional handling and the stresses of centrifugation.

Similarly filtering the aspirate is also imprecise in that the tendency of cells to be in clusters affects the filtering process.

Images