**8. Skin burn healing**

nonirradiated HSFs cultured in the same medium. LLLT with 2 J/cm2

404 Wound Healing - New insights into Ancient Challenges

of blood glucose. A diode laser (50 mW, 660 nm, 4 J/cm2

0.5, 1, and 2 J/cm2

with an 80 Hz frequency and 0.03 J/cm2

secretin of bFGF and IL‐6 from fibroblast cultured in media mentioned above (hyperglycemic condition media). When HSFs were cultured in physiologic glucose concentration medium during laser irradiation, LLLT more effectively released IL‐6 and bFGF [27]. In a single case study, Dixit et al. outlined the possible effect of LLLT on delayed wound healing and pain in a diabetic patient with chronic dehiscent sternotomy. After irradiation, they observed prolif‐ eration of healthy granulation tissue with decreased scores from the pressure ulcer scale of healing for sternal According to the results, LLLT could be a new potential treatment for chronic sternal dehiscence following coronary artery bypass graft, as it reinforced wound healing with an early closure of the wound deficit [28]. Fathabadie et al. conducted a study on the influence of PW LLLT on mast cells in wounds of nondiabetic and diabetic rats. The induction of type I DM and LLLT protocol was the same as Sharifian et al.'s study [25]. They assessed mast cell numbers and degranulation in all subgroups at 4, 7, and 15 days after infliction of the wounds. According to the paired *t*‐test, there were significantly more total numbers of laser‐treated mast cells compared to the placebos in the nondiabetic and diabetic groups. They observed significantly more granulated mast cells compared with degranulated mast cells for all laser‐treated mast and placebo mast cells in the nondiabetic and diabetic groups [29]. Aparecida Da Silva et al. performed a study not only to determine if LLLT restored the balance between mRNA expression of matrix metalloproteinases (MMP)‐2 and MMP‐9 but also to determine the ratio between collagen types I and III during the diabetic wounds healing. The diabetes model was induced efficiently by STZ as demonstrated through increased levels

scare induction. After LLLT, the rats were euthanized. The scarred areas were collected for MMP‐2 and MMP‐9 mRNA and histological analyses (inflammation and types I and III collagen). The results determined that scare significantly increased MMP‐2 and MMP‐9 expressions in untreated diabetic rats compared to nondiabetic rats. LLLT significantly reduced MMP‐2 and MMP‐9 expressions compared with untreated diabetic rats. Aparecida Da Silva et al. concluded that LLLT altered the expression of MMP‐9, stimulated collagen production, and increased the total percentage of collagen type III in diabetic animals [30]. Esmaeelinejad et al. evaluated the effects of LLLT on HSFs cultured in high glucose concen‐ tration medium. HSFs were cultured either in physiologic glucose (5.5 mM/l) or high glucose (11.1 and 15 mM/l) media. LLLT was performed with a He‐Ne laser unit at energy densities of

assay. The results indicate that LLLT stimulate the viability and proliferation rate of HSFs, which were cultured in physiologic glucose medium compared to their control cultures. LLLT had stimulatory effects on the proliferation rate of HSFs cultured in high glucose concentra‐ tions compared with their control cultures. Esmaeelinejad et al. announced that HSFs origi‐ nally cultured for 2 weeks in high glucose concentration attended to culture in physiologic glucose during laser irradiation increase cell viability and proliferation. Therefore, LLLT had a stimulatory effect on these HSFs [31]. Dadpay et al. studied the effect of LLLT in experimen‐ tally induced diabetic rats. They generated two full thickness skin incisions on the dorsal regions of each rat. The healthy (nondiabetic) groups received a pulsed‐infrared 890 nm laser

. The viability and proliferation rate of these cells were determined by MTT

for each wound point in the first group and 0.2 J/cm2

energy density enhanced

, 80 s) was administered once after

Burn injuries are common traumatic injuries that cause considerable mortality and morbidity. Additionally, they are among the most expensive traumatic injuries due to the extended hospitalization and rehabilitation, as well as costly wound and scar treatments [36]. Annually in the United States, 1.25 million burn patients are treated. Of these, at least 50,000 require hospitalization [36]. Burn wounds generate special interest due to the large numbers of burn cases encountered. These wounds can generate a destructive effect functionally and cosmeti‐ cally, which necessitates the search for a more efficient cure [37]. LLLT has beneficial effects on burn healing.

### **9. Literature review**

Khoshvaghti et al. studied the effects of LLLT on mast cells in a third‐degree burn rat model. Rats from all groups each received third‐degree burns at three different locations. The first burn site on group I rats subjected to 890 nm pulsed laser, with 0.924 J/cm2 energy density. 0.2% nitrofurazone cream was administrated for treatment of the second burn site on both groups of rats. They evaluated mast cell degranulation and numbers at each burn site on each group of rats. Analysis of variance on day 4 showed significantly lower total numbers of mast cells in the laser‐treated burn sites compared with the other burn sites in both groups of rats. On day 8, the total numbers of mast cells were significantly lower at the laser‐treated burn sites compared with the other burn sites. On day 13, there were significantly lower numbers of types I and II mast cells at the laser‐treated burn sites compared with the other burn sites. Khoshvaghti et al. [38] concluded that LLLT significantly declined total numbers of mast cells through the proliferation and remodeling phases of healing in a rat model of third‐degree burn. Ezzati et al. investigated the influence of PW LLLT on healing of a deep second‐degree burn model in rats. In their study, two groups of laser‐treated burns were treated by a 3000 Hz pulsed infrared diode laser that had 2.3 or 11.7 J/cm2 energy densities, respectively. Treatment response was assessed both microbiologically and macroscopically. The incidence of *Staphylococcus aureus* diminished significantly in group 3 in comparison to group 1 on day 28. Analysis of variance showed that the 11.7 J/cm2 LLLT significantly increased the wound closure rate at 2 and 3 weeks after infliction of the burn when compared with placebo burns. Independent sample *t*‐tests demonstrated that LLLT with 11.7 J/cm2 significantly enhance the wound closure rate though 4 weeks after infliction of the burn in comparison to the control burns. Ezzati et al. concluded that pulsed LLLT with 11.7 J/cm2 /890 nm of a deep second‐ degree burn model in rats significantly escalated the rate of wound closure compared with the control burns [39]. Ezzati et al. studied the influence of PW LLLT on the healing process of a third‐degree burn in a rat model. They treated two groups of rats with a 3000 Hz‐pulsed infrared diode laser that had 2.3 or 11.7 J/cm2 energy densities and evaluated the response to treatment both microbiologically and macroscopically. They indicated that the incidence of *Staphylococcus epidermidis*, Lactobacillus, and Diphtheria diminished significantly in the laser‐ treated groups compared to the other groups by the chi‐square test. The independent sample *t*‐test illustrated that LLLT with 11.7 J/cm2 energy density significantly escalated the wound‐ closure rate at 3 and 4 weeks after infliction of the burn compared with the control burns [40]. Vasheghani et al. evaluated 80 Hz pulsed infrared diode LLLT for third‐degree burn healing in rats. The laser‐treated burns were exposed to an 80 Hz pulsed 890 nm infrared diode laser at 0.396 J/cm2 , three times per week. Burn wounds were clinically examined. There were a significantly higher number of laser‐treated burns that closed compared to the controls. The hospitalization [36]. Burn wounds generate special interest due to the large numbers of burn cases encountered. These wounds can generate a destructive effect functionally and cosmeti‐ cally, which necessitates the search for a more efficient cure [37]. LLLT has beneficial effects on

Khoshvaghti et al. studied the effects of LLLT on mast cells in a third‐degree burn rat model. Rats from all groups each received third‐degree burns at three different locations. The first

0.2% nitrofurazone cream was administrated for treatment of the second burn site on both groups of rats. They evaluated mast cell degranulation and numbers at each burn site on each group of rats. Analysis of variance on day 4 showed significantly lower total numbers of mast cells in the laser‐treated burn sites compared with the other burn sites in both groups of rats. On day 8, the total numbers of mast cells were significantly lower at the laser‐treated burn sites compared with the other burn sites. On day 13, there were significantly lower numbers of types I and II mast cells at the laser‐treated burn sites compared with the other burn sites. Khoshvaghti et al. [38] concluded that LLLT significantly declined total numbers of mast cells through the proliferation and remodeling phases of healing in a rat model of third‐degree burn. Ezzati et al. investigated the influence of PW LLLT on healing of a deep second‐degree burn model in rats. In their study, two groups of laser‐treated burns were treated by a 3000

Treatment response was assessed both microbiologically and macroscopically. The incidence of *Staphylococcus aureus* diminished significantly in group 3 in comparison to group 1 on day

closure rate at 2 and 3 weeks after infliction of the burn when compared with placebo burns.

wound closure rate though 4 weeks after infliction of the burn in comparison to the control

degree burn model in rats significantly escalated the rate of wound closure compared with the control burns [39]. Ezzati et al. studied the influence of PW LLLT on the healing process of a third‐degree burn in a rat model. They treated two groups of rats with a 3000 Hz‐pulsed

treatment both microbiologically and macroscopically. They indicated that the incidence of *Staphylococcus epidermidis*, Lactobacillus, and Diphtheria diminished significantly in the laser‐ treated groups compared to the other groups by the chi‐square test. The independent sample

closure rate at 3 and 4 weeks after infliction of the burn compared with the control burns [40]. Vasheghani et al. evaluated 80 Hz pulsed infrared diode LLLT for third‐degree burn healing in rats. The laser‐treated burns were exposed to an 80 Hz pulsed 890 nm infrared diode laser

significantly higher number of laser‐treated burns that closed compared to the controls. The

, three times per week. Burn wounds were clinically examined. There were a

energy density.

energy densities, respectively.

significantly enhance the

/890 nm of a deep second‐

LLLT significantly increased the wound

energy densities and evaluated the response to

energy density significantly escalated the wound‐

burn site on group I rats subjected to 890 nm pulsed laser, with 0.924 J/cm2

Hz pulsed infrared diode laser that had 2.3 or 11.7 J/cm2

Independent sample *t*‐tests demonstrated that LLLT with 11.7 J/cm2

burns. Ezzati et al. concluded that pulsed LLLT with 11.7 J/cm2

28. Analysis of variance showed that the 11.7 J/cm2

infrared diode laser that had 2.3 or 11.7 J/cm2

*t*‐test illustrated that LLLT with 11.7 J/cm2

at 0.396 J/cm2

burn healing.

**9. Literature review**

406 Wound Healing - New insights into Ancient Challenges

paired Student's *t*‐test indicated that the wound closure rate of laser‐treated burns was significantly longer than the control burns. Chi‐square tests showed no significant difference between each microorganism (*Staphylococcus epidermis*, *S. aureus*, and *Pseudomonas aerugino‐ sa*). Vasheghani et al. concluded that LLLT with an 80 Hz pulsed infrared diode laser accelerated third‐degree burn healing in rats [41]. Bayat et al. studied the effects of LLLT on mast cell number during the inflammation, proliferation, and remodeling phases of the wound healing process of experimental burns. In the two laser‐treated groups, burned areas were subjected to the LLLT with a He‐Ne laser at energy densities of 38.2 or 76.4 J/cm2 . They observed that on day 7 in the first laser group, there were significantly more total numbers of mast cells compared with the other groups. On day 16 in the nitrofurazone‐treated group, the total number of mast cells was significantly higher compared with the control, first laser, and normal groups [42]. In another study, Vashghani et al. investigated the effect of LLLT administered with a He‐Ne laser on mast cell number and degranulation in rats with second‐ degree burns. All rats received deeply inflicted second‐degree burns. In the two laser‐treated groups, the burns received daily LLLT, with energy densities of 1.2 or 2.4 J/cm2 . In the fifth group, the burns were treated topically with daily administration of 0.2% nitrofurazone cream. Vashghani et al. concluded that administration of LLLT for deep second‐degree cutaneous burns in rats not only significantly enhanced the number of intact mast cells during the inflammatory and proliferative phases of healing but also diminished the total number of mast cells during the remodeling phase [43]. In another study, Bayat et al. researched the effects of LL He‐Ne LT on burn healing. The two laser treated groups, underwent daily treatment with LL He‐Ne LT at energy densities of 1.2 or 2.4 J/cm2 . The response to treatment was assessed histologically and microbiologically. Analysis of variance demonstrated significantly greater mean blood vessel sections in the 1.2 J/cm2 laser group compared with the other groups. Compared with the nitrofurazone‐treated group, the mean depth of new epidermis in the 2.4 J/cm2 laser group on day 16 was significantly lower. *P. aeruginosa* and *S. aureus* grew in more than 50% of samples obtained from control group, however these bacteria did not grow in the samples from the 2.4 J/cm2 laser group. Bayat et al. concluded that LL He‐Ne LT stimulated the destruction of *S. aureus* and *P. aeruginosa* in rats with third‐degree burns. However, the histological evaluation demonstrated that LL He‐Ne LT not only made a significant escalation in the mean blood vessel sections on day 7 after infliction of the third degree burns but also reduced the mean of the depth of new epidermis on day 16 after infliction of these burns in rats [44]. Bayat et al. studied the effects of two different doses of LLLT on healing deep second‐degree burns. They inflicted a deep second‐degree burn in each rat. The control group burns remained untreated. The two laser treated group burns were irradiated daily with LL He‐Ne LT with energy densities of 1.2 or 2.4 J/cm2 . The response to treatments was assessed histologically and microbiologically. *S. epidermidis* was found in the 70% of the rats' wounds in the laser‐treated groups in comparison to 100% of rats in the control group. Despite the fact that they found *S. aureus* in 40% of the rat wounds which were treated by nitrofurazone, they did not find this bacterium in the wounds of the laser treated and control groups. Bayat et al. determined that LLLT of deep second‐degree burns made significant reduction in the number of macrophages and depth of the new epidermis. Moreover, this treatment diminished the incidence of *S. epidermidis* and *S. aureus* [45]. It seems that special LLLT protocols have potential antimicrobial activity.
