BACKGROUND Diabetic foot ulcers are a common diabetic complication leading to alarming figures of amputation, disability, and early mortality. The diabetic glucooxidative environment impairs the healing response, promoting the onset of a ‘wound chronicity phenotype’. In 50% of ulcers, these non-healing wounds act as an open door for developing infections, a process facilitated by diabetic patients’ dysimmunity. Infection can elicit biofilm formation that worsens wound prognosis. How this microorganism community is able to take advantage of underlying diabetic conditions and thrive both within the wound and the diabetic host is an expanding research field.
OBJECTIVES 1) Offer an overview of the major cellular and molecular derangements of the diabetic healing process versus physiological cascades in a non-diabetic host. 2) Describe the main immunopathological aspects of diabetics’ immune response and explore how these contribute to wound infection susceptibility. 3) Conceptualize infection and biofilim in diabetic foot ulcers and analyze their dynamic interactions with wound bed cells and matrices, and their systemic effects at the organism level. 4) Offer an integrative conceptual framework of wound–dysimmunity–infection–organism damage.
EVIDENCE AQUISITION We retrieved 683 articles indexed in Medline/PubMed, SciELO, Bioline International and Google Scholar. 280 articles were selected for discussion under four major subheadings: 1) normal healing processes, 2) impaired healing processes in the diabetic population, 3) diabetic dysimmunity and 4) diabetic foot infection and its interaction with the host.
DEVELOPMENT The diabetic healing response is heterogeneous, torpid and asynchronous, leading to wound chronicity. The accumulation of senescent cells and a protracted inflammatory profile with a pro-catabolic balance hinder the proliferative response and delay re-epithelialization. Diabetes reduces the immune system’s abilities to orchestrate an appropriate antimicrobial response and offers ideal conditions for microbiota establishment and biofilm formation. Biofilm–microbial entrenchment hinders antimicrobial therapy effectiveness, amplifies the host’s pre-existing immunodepression, arrests the wound’s proliferative phase, increases localized catabolism, prolongs pathogenic inflammation and perpetuates wound chronicity. In such circumstances the infected wound may act as a proinflammatory and pro-oxidant organ superimposed onto the host, which eventually intensifies peripheral insulin resistance and disrupts homeostasis.
CONCLUSIONS The number of lower-limb amputations remains high worldwide despite continued research efforts on diabetic foot ulcers. Identifying and manipulating the molecular drivers underlying diabetic wound healing failure, and dysimmunity-driven susceptibility to infection will offer more effective therapeutic tools for the diabetic population.
KEYWORDS Diabetic foot, amputation, infections, biofilms, microbiota
Lower-extremity diabetic ulcers are responsible for 80% of annual worldwide nontraumatic amputations. Epidermal growth factor (EGF) reduction is one of the molecular pillars of diabetic ulcer chronicity, thus EGF administration may be considered a type of replacement therapy. Topical EGF administration to improve and speed wound healing began in 1989 on burn patients as part of an acute-healing therapy. Further clinical studies based on topically administering EGF to different chronic wounds resulted in disappointing outcomes. An analysis of the literature on unsuccessful clinical trials identified a lack of knowledge concerning: (I) molecular and cellular foundations of wound chronicity and (II) the pharmacodynamic requisites governing EGF interaction with its receptor to promote cell response. Yet, EGF intra- and perilesional infiltration were shown to circumvent the pharmacodynamic limitations of topical application. Since the first studies, the following decades of basic and clinical research on EGF therapy for problem wounds have shed light on potential uses of growth factors in regenerative medicine. EGF’s molecular and biochemical effects at both local and systemic levels are diverse: (1) downregulation of genes encoding inflammation mediators and increased expression of genes involved in cell proliferation, angiogenesis and matrix secretion; (2) EGF intervention positively impacts both mesenchymal and epithelial cells, reducing inflammation and stimulating the recruitment of precursor circulating cells that promote the formation of new blood vessels; (3) at the subcellular level, upregulation of the EGF receptor with subsequent intracellular trafficking, including mitochondrial allocation along with restored morphology of multiple organelles; and (4) local EGF infiltration resulting in a systemic, organismal repercussion, thus contributing to attenuation of circulating inflammatory and catabolic reactants, restored reduction-oxidation balance, and decreased toxic glycation products and soluble apoptogenic effectors. It is likely that EGF treatment may rearrange critical epigenetic drivers of diabetic metabolic memory.
KEYWORDS Epidermal Growth Factor, diabetes, diabetes complications, wound healing, diabetic foot, amputation, ulcer, Cuba
INTRODUCTION Diabetic foot ulcers are a chronic complication in patients with diabetes mellitus. They appear as a result of the combination of diabetic polyneuropathy and angiopathy, and in many cases require amputation of the affected extremity. Clinical trials have demonstrated that repeated local infiltration with Heberprot-P can improve healing of chronic diabetic foot ulcers. Although there is evidence of its effects as a granulation stimulator and on cell migration and proliferation, genetic control mechanisms explaining its anti-inflammatory and oxidative stress reduction properties are not yet thoroughly understood.
OBJECTIVE Analyze changes in expression of genes involved in healing after treatment of diabetic foot ulcers with Heberprot-P.
METHODS Biopsies were collected from diabetic foot ulcers of 10 responding patients before and after 2 weeks’ treatment with Heberprot-P (75-μg applied intralesionally 3 times per week). Total RNA was obtained and quantitative PCR used to determine expression of 26 genes related to inflammation, oxidative stress, cell proliferation, ngiogenesis and extracellular matrix formation. Genetic expression was quantified before and after treatment using REST 2009 v2.0.13.
RESULTS After treatment, there was a statistically significant increase in expression of genes related to cell proliferation, angiogenesis and formation of extracellular matrix (PDGFB, CDK4, P21, TP53, ANGPT1, COL1A1, MMP2 and TIMP2). A significant decrease was observed in gene expression related to inflammatory processes and oxidative stress (NFKB1, TNFA and IL-1A).
CONCLUSIONS Our findings suggest that Heberprot-P’s healing action on diabetic foot ulcers is mediated through changes in genetic expression that reduce hypoxia, inflammation and oxidative stress, and at the same time increase cell proliferation, collagen synthesis and extracellular matrix remodeling. The kinetics of expression of two genes related to extracellular matrix formation needs further exploration.
KEYWORDS Epidermal growth factor, EGF, diabetic foot ulcer, wound healing, quantitative real-time PCR, gene expression, Cuba
La úlcera del pie diabético es una de las principales complicaciones de la diabetes mellitus. Se ha demostrado que los diabéticos tienen una reducción de las concentraciones de los factores de crecimiento en sus tejidos, en particular del factor de crecimiento epidérmico. Esta reducción perjudica la cicatrización de las heridas, conduce a la cronicidad del trastorno y eventualmente a la amputación. La úlcera del pie diabético isquémico es la más difícil de tratar y tiene el mayor riesgo de amputación.
La inyección del factor de crecimiento epidérmico en los planos profundos y los bordes de la úlcera, estimula una respuesta farmacodinámica más eficaz del crecimiento del tejido de granulación y del cierre de la herida. El factor de crecimiento epidérmico que se inyecta en el nicho de la úlcera también puede asociarse con otras proteínas celulares externas al nicho, aumentando así la proliferación y la migración celular.
El Heberprot-P es un producto cubano novedoso, que contiene factor de crecimiento epidérmico humano recombinante para la infiltración perilesional e intralesional. Las evidencias muestran que acelera la curación de las úlceras profundas y complejas, tanto isquémicas como neuropáticas, y reduce las amputaciones relacionadas con la diabetes.
Los ensayos clínicos del Heberprot-P en pacientes con úlceras del pie diabético han demostrado que la infiltración local repetida de este producto puede mejorar la cicatrización de las heridas crónicas con seguridad y eficacia. Como resultado, el Heberprot-P se registró en Cuba en 2006 y en 2007 fue incluido en el Cuadro Básico de Medicamentos y aprobado para su comercialización. Su registro en otros 21 países ha permitido el tratamiento de más de 150 000 pacientes.
El Heberprot-P es el tratamiento único para las úlceras crónicas más complicadas y rebeldes, por lo general asociadas con el riesgo de amputación. La inyección local en úlceras diabéticas complejas ha demostrado una favorable relación riesgo-beneficio al acelerar la curación, reducir la recurrencia y atenuar el riesgo de amputación. La realización de otros ensayos y la extensión mundial del Heberprot-P brindarían la oportunidad de evaluar las potencialidades del producto para enfrentar una importante necesidad médica no satisfecha.
PALABRAS CLAVE úlcera del pie diabético, Heberprot-P, amputación, curación, necesidad médica insatisfecha, EGFhr, Cuba
Diabetic foot ulcer is a principal diabetic complication. It has been shown that diabetic patients have decreased growth factor concentrations in their tissues, particularly epidermal growth factor. Growth factor shortage impairs wound healing, which leads to chronic nonhealing wounds and sometimes eventual amputation. Ischemic diabetic foot ulcer is the most difficult to treat and confers the highest amputation risk.
Injecting epidermal growth factor deep into the wound bottom and contours encourages a more effective pharmacodynamic response in terms of granulation tissue growth and wound closure. Epidermal growth factor injected into the ulcer matrix may also result in association with extracellular matrix proteins, thus enhancing cell proliferation and migration.
Heberprot-P is an innovative Cuban product containing recombinant human epidermal growth factor for peri- and intra-lesional infiltration; evidence reveals it accelerates healing of deep and complex ulcers, both ischemic and neuropathic, and reduces diabetes-related amputations.
Clinical trials of Heberprot-P in patients with diabetic foot ulcers have shown that repeated local infiltration of this product can enhance healing of chronic wounds safely and efficaciously. As a result, Heberprot-P was registered in Cuba in 2006, and in 2007 was included in the National Basic Medications List and approved for marketing. It has been registered in 15 other countries, enabling treatment of more than 100,000 patients.
Heberprot-P is a unique therapy for the most complicated and recalcitrant chronic wounds usually associated with high amputation risk. Local injection in complex diabetic wounds has demonstrated a favorable risk–benefit ratio by speeding healing, reducing recurrences and attenuating amputation risk. Further testing and deployment worldwide of Heberprot-P would provide an opportunity to assess the product’s potential to address an important unmet medical need.
KEYWORDS Diabetic foot ulcer, Heberprot-P, amputation, healing, unmet medical need, rhEGF, Cuba
© The Authors. Journal Compilation © 2009 Blackwell Publishing Ltd and Medicalhelplines.com Inc. International Wound Journal, 2009, Vol 6, No 1 pages: 67–72. ABSTRACT Previous studies have shown that an epidermal growth factor-based formulation (Heberprot-P) can enhance granulation of high-grade diabetic foot ulcers (DFU). The aim of this study was to explore the clinical effects […]
