Injection of platelet aggregates in facial rejuvenation: a systematic review

ABSTRACT

factors, which are able to facilitate collagen fibroblasts, increasing the proliferation of keratinocytes and the generation of hyaluronic acid, thus increasing, dermal elasticity 1,[3][4][5] .In addition, a study proved that PRP in conjunction with aesthetic facial fat filling significantly reduced the post-treatment recovery time, thus favoring overall patient satisfaction 6 .

INTRODUCTION
Currently, physical appearance is directly related to self-esteem, which also influences the acceptance of others 1 .A decrease of vascularization, the replacement of cells, fat atrophy, and loss of muscle tonus are some of the factors that trigger skin aging 2 .In addition, the combination of genetic factors (intrinsic aging) with environmental factors (photo aging) directly influences skin aging, a common biological process, which triggers clinical manifestations such as wrinkles, alteration of surface texture, and pigmentation, among others 3 .Thus, the treatment of facial rejuvenation is increasingly being exploited for a more effective and lasting achievement 1 .
Aesthetic facial rejuvenation can be divided into operational and non-operational procedures 2 .Operating procedures include facial liposculpture surgery, a procedure in which the tissues are carved with filling using intricate layers of infiltrated autologous tissue like fat for example 4 .

Eligibility criteria
Randomized clinical trials (RCTs) with parallel or split face designs in humans comparing the technical use of facial rejuvenation alone versus the technical use of facial rejuvenation together with platelet aggregates were included.The RCTs were excluded if: 1) they performed different rejuvenating treatments associated with platelet aggregates on both sides; 2) the comparison of the use of the treatment together or separate from the platelet aggregates was not directly related to facial rejuvenation.

Study selection and data collection process
Articles were selected considering the titles first, followed by the abstract, and then articles in their entirety, in accordance with the eligibility criteria described.Relevant information from each article selected such as the study design, number and age of participants, interventions, evaluation time, and number of patients lost during treatment (Chart 2), as well as the methods of evaluations of the results (Chart 3) were extracted by researchers (C.F.AQ, C.T.T) using a personalized file.

Risk of bias of individual studies
The assays were examined using the Cochrane risk-of-bias tool of the Cochrane Collaboration 8 .
The evaluation criteria included five items: suitable generation of sequences, allocation concealment, blinding of evaluators and participants, incomplete data results and reports, and selective outcome.The risk of bias for each aspect of quality assessment was in accordance with the recommendations described in the Cochrane Handbook for Systematic Reviews 5.1.0(http://handbook.cochrane.org) 8.
Two of the five areas of Cochrane risk of bias were considered as key areas (randomization and allocation), thus qualifying the studies as "Low risk" of bias if there was an adequate sequence generation and allocation concealment.If one or more criteria were not met, the study would be considered "high" risk of bias and judged as "undefined" when the authors did not report how randomization or allocation was performed.

Study selection
After screening the databases and removing duplicates, 5918 studies were identified (Figure 1).After the removal by titles, 378 studies remained.This number was reduced to 10 after reading the abstracts and full texts were evaluated to verify eligibility.Among them, 6 were excluded: 1) four for not including rejuvenation [9][10][11][12] , 2) one for not comparing one technique to another 13 , 3) one due to unavailable full text 14 , and 1 pilot clinical case was added because the information provided fit the proposed subject 5 .

Characteristics of the studies included
The qualitative synthesis of the four studies included in this review revealed that three presented a study design with a split face 1,3,4 and one was a pilot study 5 .The studies included presented the following comparisons of Fat + PRP x Fat + FRP (Fibrin Rich Plasma), in which the main expectation was facial rejuvenation through facial filling in the cheek/malar region, to refine the facial contour 4 ; mesotherapy x PRP, in which the expectation was facial rejuvenation by intradermal injection of a solution of readymade growth factors -mesotherapy (side A) and PRP (side B) to decrease the signs of aging such as wrinkles, sagging, and pigmentary changes 3 (Chart 4).
In the study comparing mesotherapy x PRP, evaluations were performed by the evaluators one and six months after the last treatment session by using the Global Aesthetic Improvement Scale (GAIS) through a comparison of photos, besides the Patient Satisfaction Level (PSL), registering their opinion on the benefits of the treatment, and by Optical Coherence Tomography  (((((((((  #1 (((MH:Rejuvenation OR MH:"Skin Aging" OR "Adults humans" OR "Adultos humanos" OR "Humanos Adultos" OR "Adult human" OR "Adulto humano" OR "Humano adulto" OR Wrinkles OR Arrugas OR Rugas OR "Expression marks" OR "Marcas de expression" OR "Marcas de expressão"))) #2 (tw:((MH:"Plasma skin regeneration" OR MH:"Platelet rich plasma" OR MH:Fibrin OR MH:"Platelet aggregation" OR MH:"Blood platelets" OR MH:Injections OR MH:Injection OR MH:"Growth factors" OR "Platelet rich fibrin" OR "Plaquetas ricas em fibrina" OR "Plaquetas ricas en fibrin" OR PRP OR PRF OR "Skin regeneration" OR "Regeneração da pele" OR "Regeneración de la piel" OR "Platelet concentration" OR "Concentração plaquetaria" OR "Concentración plaquetaria")))  (OCT), comparing epidermal and dermal thickness.Despite the absence of a significant difference (p>0.05) in improvement between the two treated areas by the GAIS and OCT, PSL was significantly higher (p<0.05) in area B (PRP) 3 .
In the study with ultra-pulsed fractional CO 2 laser + injection of PRP, evaluations were performed three months after the last treatment session by using the VISIA Complexion Analysis System, also by the comparison of photos, which presented a statistical difference in texture and elasticity (p<0.05) that was higher for the side with the application of ultra-pulsed fractional CO 2 laser + injection of PRP.Moreover, the PSL of patients who registered their opinion about the benefits of the treatment also showed no significant difference (p<0.05), with results favorable to the ultrapulsed fractional CO 2 laser experimental group + injection of PRP 1 .
In the pilot study, the evaluations were performed one month after the last treatment session, through the application of the GAIS Scale by evaluators through comparison of photos and PSL, registering their opinion about the benefits of the treatment; and, by the histological analysis in which 3 of 7 factors analyzed presented a statistically significant difference (p<0.05), which were higher for the Fractional Laser therapy + PRP 5 .
Regarding adverse effects, there were no cases of massive edema, prolonged hematomas, or severe pain in the study of facial liposculpture surgery 4 .When comparing the mesotherapy and PRP treatments, a transient erythema was observed on both sides, which resolved in two days; there was a statistically significant difference in relation to burning sensation (p> 0.01), which was higher on the mesotherapy side 3 .Erythema, edema, and crusting were evaluated, and were significantly (p >0.05) lower on the ultra-pulsed fractional CO 2 laser + PRP side 1 .In the pilot study, there were no serious or persistent side effects during treatment.The duration of erythema was 1-3 days, with no significant difference between the two groups (p >0.05) 5 .
Compared to the FRP, PRP presented lower efficacy in relation to the maintenance of facial filling with fat.However, when associated with the other treatment and when compared to mesotherapy, its effectiveness was superior both in the improvement of rejuvenation and the reduction of adverse effects.

Assessment of risk of bias
The assessment of risk of bias of the articles selected is shown in Figure 2. Some authors did not report how concealment of allocation was performed.One study was determined to have a "low» risk of bias (reference), one study presented an "undefined" risk of bias, and the other two were classified as having a "high" risk of bias.

DISCUSSION
The main idea behind the use of platelet aggregates together with another technique of facial rejuvenation involves the bioregenerative action of PRP that stimulates the removal of components of the extracellular matrix and induces the synthesis of new collagen by dermal fibroblasts, thus increasing skin  elasticity 2,15 .The present systematic review was carried out to clarify this issue.
Half of the studies included in this systematic review reported no significant differences in the results when comparing the two types of treatment 3,5 .Although all selected papers reported expected results in accordance with the objective, the other key areas were classified as "undefined" or with a "high" risk of bias, thus reducing the reliability of the results.
Fat grafts have always been a challenge when inducing the necessary neoangiogenesis in facial liposculpture surgery, which results in significant resorption.Some studies have indicated that FRP provides better fat graft survival compared to PRP due to its retention and the slow release of platelet growth factors 4 .
To reduce this resorption, a study was carried out to compare the efficiency of PRP versus FRP combined with a fat graft.The results indicated that FRP associated with fat is more effective than a combination of PRP and fat.The difficult injection technique and the lack of FRP fibrin clot are the main disadvantages of FRP and fat compared to PRP 4 .
In a critical review of the current literature, five of the six selected studies showed an improvement in fat graft survival with the addition of platelet preparation 16 .
Liang et al. 17 assessed the efficacy of nanofatderived stem cells (NFSCs) in facial rejuvenation by intradermal injection of nanofat combined with FRP applied in 103 patients compared to a control group of 128 patients undergoing hyaluronic acid (HA) injections.They concluded that both the injection of nanofat-FRP and HA showed an improvement in the condition of the skin, but the first was associated with a greater patient satisfaction, as well as an improvement in skin texture, suggesting that the injection of nanofat-FRP is safe, highly effective, and a long-lasting method for skin rejuvenation.
Compared to mesotherapy, PRP was superior due to increased patient satisfaction, fewer side effects, and more sustainable results, without a significant difference between the two areas treated regarding improvement according to GAIS and OCT.However, the durability of PRP compared to mesotherapy needs to be better evaluated, since the superiority of PRP was only perceived at the 6-month follow-up.This suggests a shorter life of readymade products when compared to the longevity of the effects of growth factors induced naturally by PRP, a point that suggests more detailed research with longer follow-up periods 3 .
In addition to a reduction in adverse effects, several studies have reported that PRP led to a clinical improvement when analyzing the effectiveness of PRP combined with fractional carbon dioxide laser ablation in the treatment of atrophic acne scars 21 .As the MTZ produced by ultra-pulsed CO 2 laser has similar histopathological changes to those of wounds, laser therapy associated with PRP accelerates healing and reduces the adverse effects 1 .
The results of a study involving PRP associated with an ablative carbon dioxide laser showed that despite greater patient satisfaction, there was a greater duration of adverse effects on the experimental side (with the association of PRP), although this was not statistically significant.This worsening of adverse effects can be attributed to the accumulated evidence, demonstrating that platelets contribute to the initiation and propagation of the inflammatory process 18 .
When PRP was combined with microneedling, no articles were found relating to facial rejuvenation per se, but mostly, the safety and efficacy of treatment in facial aesthetics was assessed, together with the improvement of post-acne atrophic scars.
Facial harmonization is a set of aesthetic procedures that aim to harmonize the teeth aesthetically and functionally with the mouth and face.Although it is not yet a specialty in dentistry, it is important to know the definition of the area of action, which, according to Resolution 176, dated September 6, 2016, authorizes the use of botulinum toxin and facial fillers by a dental surgeon for functional and/or aesthetic therapeutic purposes if they do not extrapolate their anatomical area of activity.
Given that the clinical-anatomical area of the dental surgeon includes above the hyoid bone, up to the nasal point (bones of the nose) and anterior to the tragus, covering adjacent structures and the like, and for the cases of non-surgical procedures, of the aesthetic purpose of facial harmonization in its breadth, it also includes the upper third of the face.
Furthermore, according to resolution 158/2015 of the Federal Official Journal, the Federal Council of Dentistry regulated the use of platelet aggregates for non-transfusion purposes in dentistry, making it possible to collect blood to obtain PRP and FRP in a dental or surgical center.This establishes that not only dermatologists, but also the qualified dental surgeons, have the possibility and competence to perform a facial rejuvenation treatment with the use of platelet aggregates.
This systematic review showed that, due to the scarce evidence and the risk of "undefined" bias, there is need for further research, especially randomized controlled trials, that test alternatives to assess the best form of application of platelet aggregates for facial rejuvenation.
Therefore, further randomized controlled clinical studies should be performed that compare the use of platelet aggregates with other facial rejuvenation techniques, since even with good results, few are found in the literature.

CONCLUSION
This systematic review found that there are few studies in the literature that compare the use of platelet aggregates in facial rejuvenation, and those that are available have an "undefined" or "high" risk of bias.Further well-designed clinical studies are needed that compare the use of platelet aggregates associated with facial rejuvenation techniques.

Chart 4 .
Summary of the results found in each study selected, in which p<0.05 represents a statistically significant difference.

Figure 1 .
Figure 1.Flowchart of the study.

Figure 2 .
Figure 2. Summary of risk of bias according to the Cochrane Collaboration tool.