# An Oxygenated Layer Coating to Enhance the Healing Process of Non-Healing Wounds--A Case Report
## 1 Introduction  
Modern medicine is struggling with the ever-increasing problem of chronic, non-healing wound treatment [1]. Chronic, non-healing wounds are associated with aging societies; the lifestyles of people in developed countries; and constantly increasing urbanization, resulting in a growing number of injuries, including traffic-related ones [2]. In addition, chronic wounds are the reason for professional absenteeism; cause individuals to withdraw from social life; and, in extreme cases, may lead to psychiatric disorders headed by depression [3]. Furthermore, considering the high cost of long-term--often lasting several months--outpatient treatment [4; 5], whose efficacy varies between patients, it is critical to provide fast-acting, effective dressings that significantly support ulcer healing. Chronic wounds are difficult-to-heal, physiologically impaired wounds/ulcers in which the normal healing process has been disrupted in one or more phases [6; 7]. In addition, the underlying pathology (e.g., comorbidities like cardiovascular disease or diabetes) usually cause a delay in the healing process. Moreover, non-physiological factors(quality of healthcare services, social context, or the patient's mental state) are also identified as aspects influencing wound healing [8]. Contemporary medicine applies several approaches to heal chronic wounds, including treatment based on managing controllable process factors (e.g., nutritional support, infection removal, and mechanical protection) [9], the targeted delivery of active agents [10], or hyperbaric oxygen therapy [11; 12] and the usage of sub-atmospheric pressure dressings [13]. In contrast, other methods are based on tissue engineering, like human skin equivalents [14] or autologous skin transplantation [15]. Other strategies might include the usage of platelet-rich plasma (PRP) [16] or the application of recombinant growth factors [17]. As a result, in therapies based on PRP, the time of patients' hospitalization can be reduced [18]. Nonetheless, due to the variable concentration of PRP and lack of standardized procedures for application, evidence from studies can be unreliable, which impedes clinical usage in patients [19; 20]. Oxygen is essential in wound healing as it participates in many processes leading to tissue restoration, including angiogenesis, fibroplasia, and cell proliferation [21; 22]. On the other hand, limiting the oxygen supply to a wound area impedes and delays healing [23]. Furthermore, it has been shown that oxygen transport to the tissue is disturbed in chronic wounds, which results in high hypoxia [21; 24], wherein extreme hyperoxia can promote the formation of reactive oxygen species, causing oxidative stress, mitochondrial apoptosis, and growth retardation [23]. Thus, it cannot be surprising that scientists are trying to improve wound healing by enhancing tissue oxygenation, such as by employing special dressings that maintain adequate oxygen levels by continuous delivery [25; 26; 27]. Incorporating oxygenating factors into plasters aimed at wound care is another possible option. Perfluorocarbons (PFCs), known for absorbing large amounts of oxygen, can be used for this purpose. PFCs have been previously applied in wound healing. For example, [PERSON] et al. described a perfluorodecalin-based supersaturated oxygen emulsion supporting eye regeneration after chemical injuries [28]. Studies on improving dressing construction for wound healing are still being developed [29; 30; 31; 32; 33]. Herein, we report cases of applying a dressing containing oxygenating factors to promote healing in hard-to-heal wounds and its effects. A subassembly of the dressing qualified for use in a clinical trial with a previously developed platform containing platelet growth factor, which consisted of a bandage support with an oxygenating coating. This study aims to assess the effectiveness and clinical usefulness of modified dressings in combination with autologous platelet-rich plasma.