Current Aspects in the Pathophysiology and Treatment of Chronic Wounds in Diabetes Mellitus
Elena Tsourdi,1 Andreas Barthel,1,2 Hannes Rietzsch,1 Andreas Reichel,1 and Stefan R. Bornstein1
1Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine III, Technical University Medical Center, 01307 Dresden, Germany
2Endokrinologikum Ruhr, 44866 Bochum, Germany
Received 28 October 2012; Accepted 6 March 2013
Academic Editor: David G. Armstrong
Copyright © 2013 Elena Tsourdi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Impaired wound healing is a frequent and very severe problem in patients with diabetes mellitus, yet little is known about the underlying pathomechanisms. In this paper we review the biology of wound healing with particular attention to the pathophysiology of chronic wounds in diabetic patients. The standard treatment of diabetic ulcers includes measures to optimize glycemic control as well as extensive debridement, infection elimination by antibiotic therapy based on wound pathogen cultures, the use of moisture dressings, and offloading high pressure from the wound bed. In this paper we discuss novel adjuvant therapies with particular reference to the use of autologous skin transplants for the treatment of diabetic foot ulcers which do not respond to standard care.
1. Introduction
The diabetic foot syndrome is a very severe and common complication in patients with diabetes mellitus with a cumulative lifetime incidence of up to 25 percent [1]. The escalating high rates of diabetes in many parts of the world make diabetic foot ulcers a major and increasing public-health problem. Foot ulcers cause substantial morbidity, impair quality of life, are the most important risk factor for lower-extremity amputation, and result in high treatment costs and enormous economic losses [2]. The factors that delay wound healing in diabetes are multiple and relate both to the impaired glucose metabolism and to the effect of neurovascular complications. Diabetic foot ulcers readily become chronic; all too often these wounds do not heal primarily. Treatment of chronic wounds should be essentially directed against the main etiologic factors responsible for the wound. Management is based on the simple principles of eliminating infection, the use of dressings to maintain a moist wound bed and to absorb exsudate, offloading high pressure from the wound bed, and debridement to accelerate endogenous healing and facilitate the effectiveness of topically applied substances [3]. Nevertheless, there are often cases of persistent diabetic foot ulcers that do not respond to standard care. In such patients, skin replacement therapies either by autologous skin transplantation or by tissue-engineered human skin equivalents are second-line options which could prevent an amputation and should therefore be considered.
2. Physiological Process of Wound Healing
The physiological process of wound healing is traditionally divided into four phases: haemostasis, inflammation, proliferation, and maturation or remodelling. These phases are orchestrated by a subtle interplay of cellular and humoral factors [4]. Haemostasis occurs within an hour after injury and is characterized by vasoconstriction and clotting. Platelets not only initiate the clotting cascade but also secrete growth factors and cytokines which initiate healing. The subsequent inflammation phase takes up to seven days and is mediated through neutrophil granulocytes which prevent bacterial contamination and cleanse the wound from cell debris. Monocytes are attracted to the wound by chemotactic factors and differentiate into wound macrophages. The latter not only remove bacteria and nonviable tissue by phagocytosis but also release various growth factors required to stimulate fibroplasia and angiogenesis, thereby providing the basis for the formation of the provisional extracellular matrix (ECM). The proliferation phase is initiated at day 2 after injury and takes up to 20 days. This phase is primarily characterized by tissue granulation and formation of new blood vessels (angiogenesis). The angiogenic process involves growth factors such as platelet-derived growth factor (PDGF), macrophage angiogenesis factor, and angiotensin. Concomitant epithelialisation is then initiated to cover the granulation tissue with a cellular barrier. The last phase involving extensive tissue remodelling lasts from one week to six months after injury. During that phase the provisional wound matrix is replaced with proteoglycan and collagen molecules which readily become organised into thicker bundles resulting in stronger but more rigid scar tissue.
3. Pathophysiology of Wound Healing in Diabetes
Wound healing in diabetes is impaired by factors that are both extrinsic and intrinsic to the wound and its biology. Extrinsic factors include repeated trauma or mechanical stress applied to a foot that has been rendered insensitive due to neuropathy as well as ischemia as a result of macro- or microvascular disease [5]. Thickening of the basement membrane of the capillaries and arterioles frequently occurs in individuals with diabetes, resulting in an impaired wound healing and persistent ulcer formation [6]. An important role has been attributed to factors intrinsic to the biology of the chronic wound in diabetes. It has been postulated that hyperglycaemia itself has a deleterious effect on wound healing through the formation of advanced glycation end-products (AGEs) which induce the production of inflammatory molecules (TNF-, IL-1) and interfere with collagen synthesis [7]. Furthermore, Spravchikov et al. showed that exposure to high glucose is associated with changes in cellular morphology, decreased proliferation, and abnormal differentiation of keratinocytes [8], thus revealing another mechanism by which hyperglycaemia may affect wound healing in diabetes. Interestingly, the healing times of leg and foot ulcers are decreased in diabetic patients with lower HbA1c, thereby emphasizing the clinical correlation between hyperglycaemia and impaired wound healing [9]. An altered immune function may also contribute to poor wound healing in patients with diabetes. Decreased chemotaxis, phagocytosis, bacterial killing [10], and reduced heat shock protein expression [11] have been implicated in the early phase of wound healing in diabetes. Fahey et al. demonstrated that altered leukocyte infiltration and wound fluid IL-6 characterize the late inflammatory phases of wound healing in diabetes [12]. It therefore seems that an altered pattern of cytokine appearance in the wound milieu may contribute to delayed wound healing in diabetes. This is substantiated by the fact that altered bioavailability of cytokines and growth factors have been implicated in the pathogenesis of chronic wounds. These signalling molecules are secreted by various cell types to control cellular proliferation, differentiation, migration, and metabolism. Abnormal expression of growth factors has been observed in diabetic foot ulcers [13]. It has been postulated that trapping of growth factors and cytokines by certain macromolecules such as albumin, fibrinogen, and 2-macroglobulin may disrupt the healing process [14]. Furthermore, increased degradation of growth factors in wound fluid of diabetic subjects has been discussed as a factor contributing to an impaired wound healing process. For example, Duckworth et al. have reported an increased activity of insulin degrading enzyme (IDE) activity in wound fluid from patients with diabetic foot ulcers [15]. Interestingly, insulin degrading activity in the wound fluid was found to be positively correlated with HbA1c levels, thereby supporting the fact that glucose control is an essential prerequisite for wound healing. In addition, normal wound healing requires a balance between the accumulation of collagenous and noncollagenous extracellular matrix components. Their remodelling is determined by matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) [16]. MMPs play essential roles in initial wound debridement as well as in angiogenesis, epithelialization, and remodelling of scar tissue [17]. Several studies reported elevated levels of MMPs and reduced levels of TIMPs in chronic wounds [18] with a similar pattern in wounds of patients with diabetes mellitus [19]. Last but not least, there is also increasing evidence that the resident cells of chronic wounds may undergo phenotypic changes that impair their capacity for proliferation and movement. For example, it has been reported that fibroblasts from venous and pressure ulcers are senescent and have a diminished ability to proliferate with the proliferative capacity being directly correlated to the failure to heal [20].
4. Standard Treatment Methods in Diabetic Foot Ulcers
The standard treatment of diabetic ulcers includes measures to assess vascular status and optimize glycemic control as well as extensive debridement, infection elimination by antibiotic therapy based on wound pathogen cultures, the use of moisture dressings, and offloading high pressure from the wound bed. Vascular assessment should include palpation of all lower-extremity pulses, including femoral, popliteal, posterior tibial, and dorsalis pedis pulses. A surrogative and more accurate method of diagnosing vascular insufficiency in the lower limbs is the use of the ankle branchial pressure index (ABPI), the results of which can be validated through Doppler waveform and pulse oximetry. In case of significant peripheral arterial disease, therapeutic revascularisation should be undertaken, since adequate vascular supply is essential for wound healing. The correlation between normoglycaemia and facilitated wound healing in diabetes has been
ด้านปัจจุบัน Pathophysiology และรักษาแผลเรื้อรังในเบาหวานTsourdi เอเลนา Barthel Andreas 1, 1, 2 Hannes Rietzsch, Reichel Andreas 1, 1 และ Stefan R. Bornstein11Division ทันต เบาหวาน และ โรคกระดูก ภาควิชาเวชศาสตร์ III ศูนย์การแพทย์มหาวิทยาลัยเทคนิค 01307 Dresden เยอรมนีRuhr 2Endokrinologikum, 44866 โบคุม เยอรมนีรับ 28 2555 ตุลาคม ยอมรับ 6 2013 มีนาคมบรรณาธิการวิชาการ: David G. อาร์มสตรองสงวนลิขสิทธิ์ © 2013 เอเลนา Tsourdi et al นี่คือบทความเข้าเปิดกระจายภายใต้การสร้างสรรค์คอมมอนส์แสดงลิขสิทธิ์ ซึ่งใช้ใบอนุญาตที่ไม่จำกัด กระจาย และการผลิตซ้ำในสื่อใด ๆ ให้ถูกต้องมีอ้างงานต้นฉบับบทคัดย่อรักษาผู้ที่มีแผลมีปัญหาบ่อยครั้ง และรุนแรงมากในผู้ป่วยที่ มีเบาหวาน ยังน้อยเป็นที่รู้จักเกี่ยวกับ pathomechanisms ต้น ในเอกสารนี้ เราตรวจสอบชีววิทยาของแผลรักษาเฉพาะพร้อม pathophysiology ของบาดแผลเรื้อรังในผู้ป่วยโรคเบาหวาน การรักษามาตรฐานของโรคเบาหวานแผลในปากรวมถึงมาตรการเพื่อเพิ่มประสิทธิภาพควบคุม glycemic ตลอดจน debridement อย่างละเอียด กำจัดเชื้อ โดยยาปฏิชีวนะรักษาตามแผลการศึกษาวัฒนธรรม การใช้แผลชื้น ถ่ายความดันสูงที่จากบาดแผล ในเอกสารนี้ เราหารือรักษาประเมินนวนิยายอ้างอิงเฉพาะเพื่อใช้สำหรับการรักษาแผลที่เท้ารองเท้าที่ไม่ตอบสนองต่อมาตรฐานการดูแลผิว autologous transplants1. บทนำกลุ่มอาการของเท้าเป็นอย่างรุนแรง และพบอาการแทรกซ้อนในผู้ป่วยที่มีเบาหวานด้วยเกิดชีวิตสะสมถึง 25 เปอร์เซ็นต์ [1] ราคาสูง escalating ของโรคเบาหวานในหลายส่วนของโลกให้เป็นโรคเบาหวานเท้าแผลเปื่อยเป็นหลักและเพิ่มปัญหาสาธารณสุข แผลที่เท้ารองเท้าทำให้เกิด morbidity พบ ทำคุณภาพชีวิต มีปัจจัยเสี่ยงที่สำคัญที่สุดสำหรับส่วนปลายล่าง amputation แล้วส่งผลให้ต้นทุนสูงในการรักษาและสูญเสียทางเศรษฐกิจมหาศาล [2] ปัจจัยที่ล่าช้าแผลในโรคเบาหวานหลาย และเชื่อมโยงทั้งการลดกระชับสัดส่วน และผลของภาวะแทรกซ้อน neurovascular แผลที่เท้ารองเท้าพร้อมเป็นเรื้อรัง ทั้งหมดบ่อยเกินไปบาดแผลเหล่านี้ไม่รักษาหลักการ รักษาแผลเรื้อรังควรจะตรงกับปัจจัย etiologic หลักที่รับผิดชอบสำหรับแผลเป็น จัดการเป็นไปตามหลักการง่าย ๆ ของการตัดติดเชื้อ การใช้แผล เพื่อรักษาบาดแผลชุ่มชื่นเตียง และซับ exsudate ถ่ายความดันสูงจากแผลเตียง debridement เร่งรักษา endogenous และอำนวยความสะดวกประสิทธิภาพของสารที่ใช้ topically [3] อย่างไรก็ตาม ได้บ่อยกรณีของแผลที่เท้าแบบรองเท้าที่ไม่ตอบสนองการดูแลมาตรฐาน ในผู้ป่วยดังกล่าว ผิวแทนที่รักษา โดยการปลูกถ่ายแบบ autologous ผิว หรือเทียบเท่าวิศวกรรมเนื้อเยื่อผิวหนังมนุษย์มีตัวเลือกสองบรรทัดซึ่งสามารถป้องกันการ amputation และดังนั้นจึงควร2. กระบวนการสรีรวิทยาของการรักษาแผลThe physiological process of wound healing is traditionally divided into four phases: haemostasis, inflammation, proliferation, and maturation or remodelling. These phases are orchestrated by a subtle interplay of cellular and humoral factors [4]. Haemostasis occurs within an hour after injury and is characterized by vasoconstriction and clotting. Platelets not only initiate the clotting cascade but also secrete growth factors and cytokines which initiate healing. The subsequent inflammation phase takes up to seven days and is mediated through neutrophil granulocytes which prevent bacterial contamination and cleanse the wound from cell debris. Monocytes are attracted to the wound by chemotactic factors and differentiate into wound macrophages. The latter not only remove bacteria and nonviable tissue by phagocytosis but also release various growth factors required to stimulate fibroplasia and angiogenesis, thereby providing the basis for the formation of the provisional extracellular matrix (ECM). The proliferation phase is initiated at day 2 after injury and takes up to 20 days. This phase is primarily characterized by tissue granulation and formation of new blood vessels (angiogenesis). The angiogenic process involves growth factors such as platelet-derived growth factor (PDGF), macrophage angiogenesis factor, and angiotensin. Concomitant epithelialisation is then initiated to cover the granulation tissue with a cellular barrier. The last phase involving extensive tissue remodelling lasts from one week to six months after injury. During that phase the provisional wound matrix is replaced with proteoglycan and collagen molecules which readily become organised into thicker bundles resulting in stronger but more rigid scar tissue.3. Pathophysiology of Wound Healing in DiabetesWound healing in diabetes is impaired by factors that are both extrinsic and intrinsic to the wound and its biology. Extrinsic factors include repeated trauma or mechanical stress applied to a foot that has been rendered insensitive due to neuropathy as well as ischemia as a result of macro- or microvascular disease [5]. Thickening of the basement membrane of the capillaries and arterioles frequently occurs in individuals with diabetes, resulting in an impaired wound healing and persistent ulcer formation [6]. An important role has been attributed to factors intrinsic to the biology of the chronic wound in diabetes. It has been postulated that hyperglycaemia itself has a deleterious effect on wound healing through the formation of advanced glycation end-products (AGEs) which induce the production of inflammatory molecules (TNF-, IL-1) and interfere with collagen synthesis [7]. Furthermore, Spravchikov et al. showed that exposure to high glucose is associated with changes in cellular morphology, decreased proliferation, and abnormal differentiation of keratinocytes [8], thus revealing another mechanism by which hyperglycaemia may affect wound healing in diabetes. Interestingly, the healing times of leg and foot ulcers are decreased in diabetic patients with lower HbA1c, thereby emphasizing the clinical correlation between hyperglycaemia and impaired wound healing [9]. An altered immune function may also contribute to poor wound healing in patients with diabetes. Decreased chemotaxis, phagocytosis, bacterial killing [10], and reduced heat shock protein expression [11] have been implicated in the early phase of wound healing in diabetes. Fahey et al. demonstrated that altered leukocyte infiltration and wound fluid IL-6 characterize the late inflammatory phases of wound healing in diabetes [12]. It therefore seems that an altered pattern of cytokine appearance in the wound milieu may contribute to delayed wound healing in diabetes. This is substantiated by the fact that altered bioavailability of cytokines and growth factors have been implicated in the pathogenesis of chronic wounds. These signalling molecules are secreted by various cell types to control cellular proliferation, differentiation, migration, and metabolism. Abnormal expression of growth factors has been observed in diabetic foot ulcers [13]. It has been postulated that trapping of growth factors and cytokines by certain macromolecules such as albumin, fibrinogen, and 2-macroglobulin may disrupt the healing process [14]. Furthermore, increased degradation of growth factors in wound fluid of diabetic subjects has been discussed as a factor contributing to an impaired wound healing process. For example, Duckworth et al. have reported an increased activity of insulin degrading enzyme (IDE) activity in wound fluid from patients with diabetic foot ulcers [15]. Interestingly, insulin degrading activity in the wound fluid was found to be positively correlated with HbA1c levels, thereby supporting the fact that glucose control is an essential prerequisite for wound healing. In addition, normal wound healing requires a balance between the accumulation of collagenous and noncollagenous extracellular matrix components. Their remodelling is determined by matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) [16]. MMPs play essential roles in initial wound debridement as well as in angiogenesis, epithelialization, and remodelling of scar tissue [17]. Several studies reported elevated levels of MMPs and reduced levels of TIMPs in chronic wounds [18] with a similar pattern in wounds of patients with diabetes mellitus [19]. Last but not least, there is also increasing evidence that the resident cells of chronic wounds may undergo phenotypic changes that impair their capacity for proliferation and movement. For example, it has been reported that fibroblasts from venous and pressure ulcers are senescent and have a diminished ability to proliferate with the proliferative capacity being directly correlated to the failure to heal [20].4. Standard Treatment Methods in Diabetic Foot UlcersThe standard treatment of diabetic ulcers includes measures to assess vascular status and optimize glycemic control as well as extensive debridement, infection elimination by antibiotic therapy based on wound pathogen cultures, the use of moisture dressings, and offloading high pressure from the wound bed. Vascular assessment should include palpation of all lower-extremity pulses, including femoral, popliteal, posterior tibial, and dorsalis pedis pulses. A surrogative and more accurate method of diagnosing vascular insufficiency in the lower limbs is the use of the ankle branchial pressure index (ABPI), the results of which can be validated through Doppler waveform and pulse oximetry. In case of significant peripheral arterial disease, therapeutic revascularisation should be undertaken, since adequate vascular supply is essential for wound healing. The correlation between normoglycaemia and facilitated wound healing in diabetes has been
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