Richard J. Miron - Understanding Platelet-Rich Fibrin

As depicted in Fig 2-32, by 90 seconds already a drop in membrane size of 13% was observed, and by 120 seconds this dropped even further. The entire goal of centrifugation is to separate layers based on density, so when blood remains sitting in a centrifugation tube for 120 seconds, it is certain that some of the fibrinogen and thrombin are beginning to convert into fibrin. Thereafter, when centri-fugation begins, it becomes harder and harder to separate layers (and most importantly cell types as a result). Therefore, centrifugation should be carried out between 60 and 90 seconds after blood draw. It generally takes 15 seconds to fill the tube with blood to begin with, sometimes even longer ( Fig 2-33).

Fig 2-32Average size of PRF membranes from 60 patients following blood draw after an initial wait period of 0, 30, 60, 90, and 120 seconds prior to centrifugation. Notice that after 90 seconds, the PRF membranes were significantly reduced in size (by 13%). Following a 120-second wait period, these membranes were further significantly reduced in size (by 23%) compared to the control (0-second wait period). * P < .05 indicates a significant difference between 0 seconds from centrifugation and the investigated time period of 90 and 120 seconds. (Adapted from Miron et al. 57)

Fig 2-33Required time interval to fill each manufacturer’s PRF tube. Note that in general it takes roughly 15 seconds, but some manufacturers have slower-filling tubes. (Adapted from Miron et al. 39)

Always remember that the entire goal of centri-fugation is to separate layers based on density. When blood sits in a centrifugation tube for 120 seconds, it is certain that some of the fibrinogen and thrombin are beginning to convert into fibrin.

One noticeable trend was that the size of the membranes produced between male and female patients was different. On average, the size of PRF membranes produced by females was 17% larger than those produced in males ( Fig 2-34). As the role of centrifugation is to separate blood layers transitionally over time, these differences were due to females generally reporting lower hematocrit levels within their peripheral blood compared to males. 58,59The same trend was also observed in older patients ( Fig 2-35). This is also due to the fact that as one ages, a lower hemat-ocrit count is usually noted, and therefore the “density” of blood is lowered (fewer RBCs). Seemingly, it is easier for blood layers to separate accordingly.

Fig 2-34 (a) Comparison of the average size of PRF membranes between males and females in 60 patients. Notice that at earlier time points, the female PRF membranes were significantly larger compared to male PRF membranes. * P < .05 indicates a significant difference between male and female PRF membrane sizes (%). (b) Bar graph representing the average size of PRF membranes from males and females in 60 patients. On average, the female PRF membranes were 17% larger. * P < .05 indicates a significant difference between male and female PRF membrane sizes (%). (Adapted from Miron et al. 57)

Fig 2-35Comparison of the average size of PRF membranes between various age groups: 21–40 years, 41–60 years, and 61–80 years. While no significant differences were noticed between the groups, in general older patients produced larger membranes. (Adapted from Miron et al. 57)

Because centrifugation separates blood based on density, it is important to note that variability will exist. Females and older patients have less hematocrit when compared to men and younger individuals. As a result, PRF clots produced in older females will be significantly larger than young males (especially young athletes or those living at high altitude). Generally, in the younger male population or patients routinely living at high altitude, a 20% increase in the RCF values of each protocol is recommended.

Conclusion

The use of GFs in dentistry has gained tremendous momentum and popularity in recent years, especially because of the easily obtainable and low-cost group of platelet concentrates. Autologous PRF is a 100% natural blood-derived tissue engineering scaffold that is totally physiologic and safe and may be utilized for the purpose of wound healing. This chapter outlined the main GFs and cell types found in PRF and further demonstrated the massive effect of centrifugation parameters on the final cell layer separation in PRF. Major advancements with respect to first utilizing the LSCC and thereafter horizontal centrifugation have more recently optimized the final production of PRF. Future research remains ongoing to further highlight all the biologic properties and advantages of PRF, such as its ability to regulate immune cells as well as participate in antimicrobial defense. In summary, PRF serves as an excellent tissue engineering scaffold by fulfilling its three main criteria: scaffold (fibrin), cells (platelets and leukocytes), and GFs (PDGF, VEGF, TGF-β).

References

1.Guo S, Dipietro LA. Factors affecting wound healing. J Dent Res 2010;89:219–229.

2.Tonnesen MG, Feng X, Clark RA. Angiogenesis in wound healing. J Investig Dermatol Symp Proc 2000;5:40–46.

3.de Almeida Barros Mourao CF, Miron RJ, de Mello Machado RC, Ghanaati S, Alves GG, Calasans-Maia MD. Usefulness of platelet-rich fibrin as a hemostatic agent after dental extractions in patients receiving anticoagulant therapy with factor Xa inhibitors: A case series. J Oral Maxillofac Surg 2019;23:381–386.

4.Gurtner GC, Werner S, Barrandon Y, Longaker MT. Wound repair and regeneration. Nature 2008;453:314–321.

5.Dohan Ehrenfest DM, Del Corso M, Diss A, Mouhyi J, Charrier JB. Three-dimensional architecture and cell composition of a Choukroun’s platelet-rich fibrin clot and membrane. J Periodontol 2010;81:546–555.

6.Ghanaati S, Booms P, Orlowska A, et al. Advanced platelet-rich fibrin: A new concept for cell-based tissue engineering by means of inflammatory cells. J Oral Implantol 2014;40:679–689.

7.Kawazoe T, Kim HH. Tissue augmentation by white blood cell-containing platelet-rich plasma. Cell Transplant 2012;21:601–607.

8.Perut F, Filardo G, Mariani E, et al. Preparation method and growth factor content of platelet concentrate influence the osteogenic differentiation of bone marrow stromal cells. Cytotherapy 2013;15:830–839.

9.Pirraco RP, Reis RL, Marques AP. Effect of monocytes/macrophages on the early osteogenic differentiation of hBMSCs. J Tissue Eng Regen Med 2013;7:392–400.

10.Gosain A, DiPietro LA. Aging and wound healing. World J Surg 2004;28:321–326.

11.Eming SA, Brachvogel B, Odorisio T, Koch M. Regulation of angiogenesis: Wound healing as a model. Prog Histochem Cytochem 2007;42:115–170.

12.Kobayashi E, Fluckiger L, Fujioka-Kobayashi M, et al. Comparative release of growth factors from PRP, PRF, and advanced-PRF. Clin Oral Investig 2016;20:2353–2360.

13.Chase AJ, Newby AC. Regulation of matrix metalloproteinase (matrixin) genes in blood vessels: A multi-step recruitment model for pathological remodelling. J Vasc Res 2003;40:329–343.