I found the recently published study by Alamdari et al1 ("Autologous Platelet-Rich Plasma and Fibrin Glue Decrease Pain Following Excision and Primary Closure of Pilonidal Sinus," May 2019) very interesting to read. However, I would like to add a comment. Pilonidal disease (PD) is a common condition that mostly affects young individuals of both sexes. Although different surgical methods are available for PD, they all have the same goal: drainage and excision of the sinus and/or abscess.2 After surgery, two of the most common wound management methods are primary closure or an open healing approach. According to one meta-analysis, the open healing approach has a lower incidence of sinus recurrence.3 However, there are some complications associated with this method, including pain, longer healing time, and patient discomfort.2

In the aforementioned article by Alamdari et al,1 treatment with platelet-rich plasma (PRP) led to reduced pain among patients who underwent the open healing approach. Mohammadi et al4 reported the same results, demonstrating that pain was reduced in a PRP-treated group in comparison with controls. Further, they showed that angiogenesis in the wound site was significantly higher in the treatment arm.4 In a different study, this author team established a significant negative association between angiogenesis and pain duration in PD patients treated with PRP (A.H.N, unpublished data, May 2019).

Wound pain could be caused by different factors, including vascular injury and ischemia.5 Moreover, studies demonstrate that skin tissue hypoxia and impaired nutrition cause severe pain in complex regional pain syndrome.6 Thus, better oxygenation and nutrient delivery, as well as repair of vascular injury, lead to a decrease in pain and acceleration of wound healing. Angiogenesis provides oxygen and nutrients to the cells, and removes waste from the cellular microenvironment.

From a physiologic perspective, angiogenesis plays a critical role in tissue regeneration and wound healing, and it has been shown that PRP could induce angiogenesis through several pathways. This process begins from the platelets' [alpha]-granules degranulation, leading to the release of different growth factors7 with a proven role in wound angiogenesis.8

In looking at current evidence, it seems that during PRP therapy angiogenesis is one of the possible mechanisms lowering the duration and/or level of pain in patients who undergo PD surgery using an open wound approach. However, further studies are necessary.

Amir Hossein Norooznezhad, MD

Medical Biology Research Center, Kermanshah University

of Medical Sciences, Kermanshah, Iran

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