Practical Method for Prevention of Fat Embolism in Mechanical Stromal Cell Applications: IPs and IV Blood Transfusion Set.

Abstract

Recently, obtaining stromal cells mechanically from adipose tissue has become very popular in plastic surgery. Mechanical methods are advantageous in terms of not only regulatory considerations but also of the application (cost, quality, and quantity) of the products obtained compared with the use of enzymes. In a study conducted by Ghiasloo et al, 4505 articles were reviewed, and it was noted that mechanical methods are used in many indications.1 Copcu and Oztan examined a total of 276 studies and found 46 different terms to define the end product from mechanical methods.2 Stromal vascular fraction is an enzyme-specific definition; the authors suggested total stromal cells (TOST) instead of stromal vascular fraction for the end product resulting from mechanical methods.2 As shown in recent studies, TOST is used in many indications, such as stromal vascular fraction.1,2 Although there are no complications related to the mechanical methods described so far, the most important potential complication is fat embolism. There is always a possibility of adipose tissue or fat globules in the final product obtained. To minimize or eliminate this risk, it is necessary to ensure that the final product is in liquid form in cases in which it is possible to enter the systemic circulation and pass through a double filter (filter in filter) in the obtained liquid.3 For this purpose, the indication-based protocols (IPs) defined by Copcu and Oztan should be followed in mechanical stromal-cell transfer.4 If the final product is to be obtained in liquid form, the condensed fat should be diluted with an appropriate liquid (saline, ringer, platelet-poor-plasma, etc.) and mechanical separation should be performed. Copcu speculated that this approach would yield more stromal cells, especially due to polarity and cellular interaction.5 In IP one, 10 cm3 condensed fat is mixed with 10 cm3 saline or similar liquid, and in IP two, 5 cm3 fat is mixed with 5 cm3 liquid and mechanical separation is achieved. To prevent embolism of TOST in liquid form, an IV transfusion with a double-filter system should be used. Today, two types of filters are used in transfusion sets: 170–200 μm filters for macroaggregates and 15–40 μm filters for microaggregates.3 Fat cells are normally 80–120 μm in size if they are not hypertrophied.3 Hypertrophied cells are retained by the macroaggregate filter and the rest by the microaggregate filter. Therefore, we use the IV set presented in Figure 1 and in the video. (See Video [online], which displays the preparation of mechanical stromal-cells). Stromal cells vary in size from 8 to 12 μm. A 25-μm filter both minimizes risk and ensures a safe delivery of stromal cells. However, the most important approach here is to obtain TOST in liquid form to prevent possible circulation of extracellular matrix and adipose tissue particles when using mechanical methods; this can only happen with IPs. Especially in the method defined as supercharged mechanical stromal-cell transfer, the addition of platelet-rich-plasma after processing the condensed fat with platelet-poor-plasma first makes it possible not only to collect approximately five times more cells but also to give both fat- and blood-derived regenerative cells, and to apply regenerative cells in a much wider spectrum. {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1.","caption":"Mechanical Stromal-cells Prep. Video 1 from “Practical Method for Prevention of Fat Embolism in Mechanical Stromal Cell Applications: IPs and IV Blood Transfusion Set.” This video displays the preparation of mechanical stromal-cells with IPs and IV filters","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_66j4389w"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} Fig. 1.: Preparation of filters for prevention of fat embolism in mechanical stromal-cell applications. A, IV blood transfusion set with 170-μm filter for macroaggregate and 25-μm filter for microaggregate. B, Filters. C, Practical set for prevention of fat embolism in mechanical stromal-cell transfer.DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. No funding was received for this article.