From the introduction of SVF to the present day, numerous therapeutic applications have been reported, including its effective role in the treatment of retinopathy and nerve regeneration [14, 15], as well as its effective role in the treatment of osteochondral disease and the treatment of myocardial infarction [16, 17]. On the other hand, the use of fractional CO2 lasers is widely applied in dermatology, such as in the treatment of striae distensae [18–21], atrophic acne scars [22–25], and burn scars [26–28].
Several studies have been performed on the methods used to treat skin scars [1, 5, 8, 9]. Among the methods used to treat skin scars in previous studies, the role of fractional CO2 laser should be mentioned [22, 23, 25, 28, 29]. Previous studies have also mentioned the efficacy of SVF in the treatment of skin scars [30–32]. Our study investigated the efficacy of combining the above two methods compared with using fractional CO2 laser alone for burn scars. The results of our study, which was designed as a double-blind clinical trial, showed significant improvement in burn scars in the group treated with fractional CO2 laser based on the average Vancouver scar scale, Cutometer.R7, complete density sonography, and skin density sonography. On the other hand, in the group treated with fractional CO2 laser along with SVF injection, the improvement of burn scar was significant based on average Vancouver scar scale, epidermal thickness sonography, complete density sonography, and dermal density sonography. And when comparing the above two groups based on the variables of Mexameter melanin index, Vancouver scar scale, overall patient and physician assessment, the group treated with SVF injection combined with fractional CO2 laser showed a significant difference in burn scar healing.
Comparing the results of the present study with similar studies, a study of facial scars caused by trauma or burns conducted by Gentil et al. in Italy in 2014 showed that 63% of scars had healed in the group treated with SVF after one year, compared with 39% in the control group and 69% in patients treated with platelet-rich plasma (PRP) and Nanofat [33].
In our study, the additional injection of SVF to fractional CO2 laser treatment was associated with an improvement in burn scar severity variables, which is consistent with the results of the above study on the role of SVF in the treatment of skin scars, including burn scars.
Other studies have been conducted on the performance of fractional CO2 laser in the treatment of skin scars. In one of these studies, the results of a meta-analysis showed that the fractional CO2 laser significantly improved the Vancouver Scar Scale score (VSS). Patient and physician scar rating scales also showed significant improvements with fractional CO2 laser treatment. In addition, the fractional CO2 laser significantly decreased the thickness of the scar measured by ultrasound [29]. In our study, the group treated with the fractional CO2 laser showed significant improvement in the Vancouver Scar Scale, Patient Global Assessment Score, and Physician Global Assessment Score.
In other results of this study, only R2 index (scar elasticity) in cutometry improved significantly with laser treatment, but measurement of R0 index (scar firmness) showed no significant improvement [29]. In our study, ultrasound and biometric findings are presented in more detail, and Complete Density Sonography, Dermal Density Sonography and Cutometery.R7 were evaluated, which confirmed a significant difference after laser treatment.
In our study, the efficacy of SVF was also evaluated. There is an evaluation that was not investigated in the above study. In our study, there was no significant difference in the R2 variable in cutometry in patients before and after laser. This difference might be due to the different nature of the study. In contrast to the aforementioned study, our study was a clinical study, whereas the aforementioned study was a systematic review.
In a 2019 study conducted in South Korea, Kim and colleagues examined a skin defect on a patient's leg that occurred after an accident. The aforementioned lesion was covered by a skin graft, but the resulting scar was prominent and developed into a hypertrophic scar. In this study, the patient was treated with fractional CO2 laser in 5 sessions, and one month later, he was treated with SVF injection and ablative CO2 laser simultaneously. The result of the examination after one year of follow-up showed that the surface of the scar had been flattened and the pigment deposits had been removed [34]. The results of this study were also consistent with our study on the simultaneous use of fractional CO2 laser and SVF injection in scar healing.
In two separate studies, Lee and his colleagues in South Korea investigated the effect of SVF injection in the surgical treatment of depressed scars. In the first study, 17 patients underwent SVF injection concurrently with surgical scar reduction. In the second study, 7 patients underwent scar revision surgery concurrently with SVF injection, and 8 patients underwent surgical treatment alone as a control group. The OSAS (Observer Scar Assessment System), SBSES (Stony Brook Evaluation System), VSS (Vancouver Scar Scale), and VAS (Visual Analogue Scale) scoring systems were used to evaluate response to treatment. All patients showed significant improvement based on all 4 scoring systems. Patients in the SVF group had a higher cure rate than the non-SVF group on all scoring systems except SBSES. The highest rate of improvement was also seen in scar height and flexibility, whereas a significant change was seen in vascularity [35].
In addition to the above studies, some studies have also investigated the effect of fractional CO2 laser in the treatment of other types of skin scars [22, 23, 25]. Nilforoushzadeh and colleagues compared two treatment methods, including fractional CO2 laser alone and fractional CO2 laser combined with subcision, in the treatment of atrophic acne scars in a clinical trial. In this study, patients with atrophic acne scars were treated with two methods, including fractional CO2 laser alone (5 sessions 3 weeks apart) on the right side of the face and fractional CO2 laser combined with subcision (subcision combined with laser in the first session and 4 fractional CO2 laser sessions 3 weeks apart after 3 weeks) on the left side of the face. Patient satisfaction was measured 6 months after treatment and side effects were compared in two treatment groups. The results showed that therapeutic efficacy was 54.7% for the combined method and 43% for the fractional CO2 laser alone method. Mean patient satisfaction based on the method VAS (visual analogue scale) was 6.6 for the combined method and 5.2 for the laser alone method. Erythema formation was observed with both methods. PIP (Postinflammatory pigmentation) and hyperpigmentation were observed only with the combined method, but after 6 months, complications did not occur in either group. The results show that the combined method achieved more effective results in improving scars and patient satisfaction. The researchers concluded that this method can be used as an efficient treatment method. However, complications such as bruising and hyperpigmentation occurred with this method, which did not occur with laser treatment alone [36]. The above results are in agreement with our study regarding the efficacy of CO2 fractional laser in the treatment of skin scars. On the other hand, it has been pointed out that the simultaneous application of multiple treatment methods is more effective in healing scars. In our study, the results confirmed the more effective use of SVF injection in combination with fractional CO2 laser compared to fractional CO2 laser alone in the treatment of burn scars.
Another study by Khan Ali and his colleagues showed that fractional CO2 laser was more effective than microneedling in reducing patients' acne scar scores. In addition, few side effects occurred with either treatment method. In addition, there was no significant difference in physician and patient satisfaction with either method [37]. The results of this study are consistent with our study regarding the efficacy of CO2 fractional laser in the treatment of skin scars. Therefore, it can be concluded that CO2 fractional laser is effective in the treatment of both burn scars and acne.
In Galal and colleagues' study of 30 patients with acne scars, the two methods of fractional CO2 laser alone and fractional CO2 laser combined with platelet-rich plasma injection (PRP) were compared, and the results of the study showed significant improvement in scar depth on both sides of the patients' faces. However, the simultaneous use of laser and PRP resulted in greater improvement in patients than laser alone. And although 70% of the patients in this study had a dark skin type, no hyperpigmentation was noted in the patients [38]. The results of this study are also consistent with our study in terms of both the efficacy of using fractional CO2 laser in scar treatment and the greater efficacy of the combined treatment compared to laser treatment alone, and in our study, the combined treatment of SVF injection and fractional CO2 laser was a significant difference in improvement in terms of Vancouver Scar Scale, Mexameter Melanin Index, Patient Global Assessment Score, Physician Global Assessment Score compared to fractional CO2 laser treatment alone.
In the study by Behrangi et al. performed in 2022 on 7 patients with acne scar complaints. All patients were treated with SVF injection in one half of the face, while the other half of the face served as a control group. The results of the evaluation after 3 months confirmed a significant improvement in sonographic variables such as skin thickness and total skin thickness compared to baseline values at the beginning of the study. In contrast, the improvement in the sonographic variable of epidermis thickness was not significant [30]. In our study, the results in the group treated with SVF in combination with fractional CO2 laser confirmed a significant improvement in melanin mexameter and Vancouver scar scale compared with fractional CO2 laser alone. There was no significant difference in the changes in skin thickness and total thickness of skin variables in the two groups. The existence of this difference could be due to the time interval between intervention and assessment. In the aforementioned study, the period between SVF injection and evaluation was three months, whereas in our study this period was two months. On the other hand, part of this difference could be due to the different nature of the scars. The mentioned study was performed on acne scars, while in our study burn scars were investigated.
Finally, it is important to mention that several studies have mentioned the efficacy of SVF in the treatment of various diseases as well as different skin lesions, including burn scars and acne scars [30, 32, 35]. The therapeutic effect of SVF is based on several mechanisms, including angiogenesis, inhibition of apoptosis, and anti-inflammatory effect [39]. And it seems that its efficacy in healing burn scars in our study is also consistent with the above effects. Based on the results of this study and other studies, the combined treatment method of CO2 laser and SVF seems to be more effective than other methods in treating scars caused by burns or other factors. The above method can be used as an alternative method in the treatment of these lesions. It should be mentioned that one of the limitations of the present study is the small sample size, which may affect the results. Therefore, conducting clinical trials with a larger sample may provide more reliable results.