Designing a Biomaterial Approach to Control the Adaptive Response to a Skin Injury

The goal of this review is to explain how to design a biomaterial approach to control the adaptive response to injury, with an emphasis on skin wounds. The strategies will be selected based on whether they have a reasonable probability of meeting the desired clinical outcome vs. just comparing the pros and cons of different strategies. To do this, the review will look at the normal adaptive response in adults and why it does not meet the desired clinical outcome in most cases. In addition, the adaptive response will be looked at in cases where it does meet the clinical performance requirements including animals that regenerate and for fetal wound healing. This will lead to how biomaterials can be used to alter the overall adaptive response to allow it to meet the desired clinical outcome. The important message of the review is that you need to use the engineering design process, not the scientific method, to design a clinical treatment. Also, the clinical performance requirements are functional, not structural. The last section will give some specific examples of controlling the adaptive response for two skin injuries: burns and pressure ulcers. For burns, it will cover some preclinical studies used to justify a clinical study as well as discuss the results of a clinical study using this system. For pressure ulcers, it will cover some preclinical studies for two different approaches: electrical stimulation and degradable/regenerative scaffolds. For electrical stimulation, the results of a clinical study will be presented.

Consensus on the application of negative pressure wound therapy of diabetic foot wounds

Because China is becoming an aging society, the incidence of diabetes and diabetic foot have been increasing. Diabetic foot has become one of the main health-related killers due to its high disability and mortality rates. Negative pressure wound therapy (NPWT) is one of the most effective techniques for the treatment of diabetic foot wounds and great progress, both in terms of research and its clinical application, has been made in the last 20 years of its development. However, due to the complex pathogenesis and management of diabetic foot, irregular application of NPWT often leads to complications, such as infection, bleeding and necrosis, that seriously affect its treatment outcomes. In 2020, under the leadership of Burns, Trauma and Tissue Repair Committee of the Cross-Straits Medicine Exchange Association, the writing group for ‘Consensus on the application of negative pressure wound therapy of diabetic foot wounds’ was established with the participation of scholars from the specialized areas of burns, endocrinology, vascular surgery, orthopedics and wound repair. Drawing on evidence-based practice suggested by the latest clinical research, this consensus proposes the best clinical practice guidelines for the application and prognostic evaluation of NPWT for diabetic foot. The consensus aims to support the formation of standardized treatment schemes that clinicians can refer to when treating cases of diabetic foot.

Effect of Hydrogel Enriched With Alginate, Fatty Acids, and Vitamins A and E on Pressure Injuries: A Case Series

Pressure injuries are a common kind of skin lesion that may be difficult to treat. The objective of this study was to analyze the effect of hydrogel enriched with alginate, fatty acids, and vitamins A and E in the treatment of pressure injuries. This case series with 12-week follow-up included applying daily dressings with hydrogel, maintaining a photographic record, using planimetry to calculate the lesion area, and classifying the healing process using the Pressure Ulcer Scale for Healing (PUSH). In addition, exudate collection from the ulcers was performed in the beginning and after 12 weeks of treatment to determine the dosage of metalloproteinase 9 (MMP9) and tissue inhibitor of metalloproteinase 1 (TIMP1). Of the 13 patients included in the study, 2 died and 11 were monitored for 12 weeks. Only 1 patient showed full wound healing, but all patients showed a significant 12.19% (p = .023) reduction in the lesion area. The PUSH score was also significantly reduced from 15.9 to 10.54 (p = .0052). Relative to the dosage of metalloproteinase and its inhibitor, there was a reduction in the level of MMP9 and there was no change in the level of TIMP1. This study showed that hydrogel enriched with alginate, fatty acids, and vitamins A and E provided promising results for the treatment of pressure injuries by reducing the lesion area, the general PUSH score, and the amount of MMP9 in the wounds' microenvironment.

Elevated Kallikrein-binding protein in diabetes impairs wound healing through inducing macrophage M1 polarization

Background

The accumulation of M1-polarized macrophages and excessive inflammation are important in the pathogenesis of diabetic foot ulcer (DFU). However, the underlying mechanism of DFU pathogenesis and the crucial regulators of DFU are less well known. Our previous study reported that kallikrein-binding protein (KBP), an angiogenesis inhibitor, was significantly upregulated in diabetic patients compared to its levels in controls. The effects of KBP on monocyte chemotaxis and macrophage M1 polarization were elucidated in this study.

Methods

Plasma KBP levels and monocyte counts were assessed by ELISA and flow cytometry. Wound closure rates in different groups were monitored daily. The phenotype and recruitment of macrophages were measured by real-time PCR, western blot and immunofluorescence assays. The expression of Notch and NF-κB signalling pathway members was determined by the methods mentioned above. ChIP and dual-luciferase reporter gene assays were employed to explore the binding and transcriptional regulation of Hes1 and iNOS.

Results

We found that plasma KBP levels and circulating monocytes were elevated in diabetic patients compared to those in nondiabetic controls, and both were higher in diabetic patients with DFU than in diabetic patients without DFU. KBP delayed wound healing in normal mice; correspondingly, KBP-neutralizing antibody ameliorated delayed wound healing in diabetic mice. Circulating monocytes and macrophage infiltration in the wound were upregulated in KBP-TG mice compared to those in control mice. KBP promoted the recruitment and M1 polarization of macrophages. Mechanistically, KBP upregulated iNOS by activating the Notch1/RBP-Jκ/Hes1 signalling pathway. Hes1 downregulated CYLD, a negative regulator of NF-κB signalling, and then activated the IKK/IκBα/NF-κB signalling pathway.

Conclusions

Our findings demonstrate that KBP is the key regulator of excessive inflammation in DFUs and provide a novel target for DFU therapy.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0376-9) contains supplementary material, which is available to authorized users.

Biomaterial Enhanced Regeneration Design Research for Skin and Load Bearing Applications

Biomaterial enhanced regeneration (BER) falls mostly under the broad heading of Tissue Engineering: the use of materials (synthetic and natural) usually in conjunction with cells (both native and genetically modified as well as stem cells) and/or biological response modifiers (growth factors and cytokines as well as other stimuli, which alter cellular activity). Although the emphasis is on the biomaterial as a scaffold it is also the use of additive bioactivity to enhance the healing and regenerative properties of the scaffold. Enhancing regeneration is both moving more toward regeneration but also speeding up the process. The review covers principles of design for BER as well as strategies to select the best designs. This is first general design principles, followed by types of design options, and then specific strategies for applications in skin and load bearing applications. The last section, surveys current clinical practice (for skin and load bearing applications) including limitations of these approaches. This is followed by future directions with an attempt to prioritize strategies. Although the review is geared toward design optimization, prioritization also includes the commercializability of the devices. This means a device must meet both the clinical performance design constraints as well as the commercializability design constraints.

Mesenchymal Stem Cells and Transforming Growth Factor-β₃ (TGF-β₃) to Enhance the Regenerative Ability of an Albumin Scaffold in Full Thickness Wound Healing

Pressure ulcers are one of the most common forms of skin injury, particularly in the spinal cord injured (SCI). Pressure ulcers are difficult to heal in this population requiring at least six months of bed rest. Surgical treatment (grafting) is the fastest recovery time, but it still requires six weeks of bed rest plus significant additional costs and a high recurrence rate. A significant clinical benefit would be obtained by speeding the healing rate of a non-surgical treatment to close to that of surgical treatment (approximately doubling of healing rate). Current non-surgical treatment is mostly inactive wound coverings. The goal of this project was to look at the feasibility of doubling the healing rate of a full-thickness defect using combinations of three treatments, for the first time, each shown to increase healing rate: application of transforming growth factor-β₃ (TGF-β₃), an albumin based scaffold, and mesenchymal stem cells (MSCs). At one week following surgery, the combined treatment showed the greatest increase in healing rate, particularly for the epithelialization rate. Although the target level of a 100% increase in healing rate over the control was not quite achieved, it is anticipated that the goal would be met with further optimization of the treatment.

Oxidized Regenerated Cellulose/Collagen Dressings: Review of Evidence and Recommendations

OBJECTIVE

Healthcare systems are being challenged to manage increasing numbers of nonhealing wounds. Wound dressings are one of the first lines of defense in wound management, and numerous options exist. The oxidized regenerated cellulose (ORC)/collagen dressing may offer healthcare providers a robust and cost-effective tool for use in a variety of wounds.

DESIGN

A multidisciplinary panel meeting was convened to discuss the use of ORC/collagen dressings in wound care and provide practice recommendations. A literature search was conducted to provide a brief review of the peer-reviewed studies published between January 2000 and March 2016 to inform the meeting.

SETTING

A 2-day panel meeting convened in February 2017.

PARTICIPANTS

Healthcare providers with experience using ORC/collagen dressings. This multidisciplinary panel of 15 experts in wound healing included podiatrists, wound care specialists (doctors, certified wound care nurses, and research scientists), and an orthopedist.

RESULTS

The literature search identified 58 articles, a majority of which were low levels of evidence (69.3% were level 3 or lower). Panel members identified wound types, such as abrasions, burns, stalled wounds, diabetic foot ulcers, and pressure injuries, where ORC/collagen dressing use could be beneficial. Panel members then provided recommendations and technical pearls for the use of ORC/collagen dressings in practice. Barriers to ORC/collagen dressing use were discussed, and potential resolutions were offered.

CONCLUSIONS

An ORC/collagen dressing can be a critical tool for clinicians to help manage a variety of wounds. Clinical and economic studies comparing standard-of-care dressings and plain collagen dressings to ORC/collagen dressings are needed.

Normalizing dysfunctional purine metabolism accelerates diabetic wound healing

Diabetic patients exhibit dysfunction of the normal wound healing process, leading to local ischemia by vascular occlusive disease as well as sustained increases in the proinflammatory cytokines and overproduction of reactive oxygen species (ROS). Of the many sources of ROS, the enzyme xanthine oxidase (XO) has been linked to overproduction of ROS in diabetic environment, and studies have shown that treatment with XO inhibitors decreases XO overactivity and XO-generated ROS. This study evaluates the role of XO in the diabetic wound and the impact of specifically inhibiting its activity on wound healing. Treatment of diabetic wounds with siXDH (xanthine dehydrogenase siRNA) decreased XDH mRNA expression by 51.6%, XO activity by 35.9%, ROS levels by 78.1%, pathologic wound burden by 31.5%, and accelerated wound healing by 7 days (23.3%). Polymerase chain reaction analysis showed that increased XO activity in wild-type wound may be due to XDH to XO conversion and/or XO phosphorylation, but not to gene transcription, whereas increased XO activity in diabetic wounds may also be from gene transcription. These results suggest that XO may be responsible for large proportion of elevated oxidative stress in the diabetic wound environment and that normalizing the metabolic activity of XO using targeted delivery of siXDH may decrease overproduction of ROS and accelerate wound healing in diabetic patients.

Macrophage stimulating agent soluble yeast β-1,3/1,6-glucan as a topical treatment of diabetic foot and leg ulcers: A randomized, double blind, placebo-controlled phase II study

AIMS/INTRODUCTION

Dysregulated inflammatory response is believed to be an important factor in the pathogenesis of several late complications of diabetes mellitus. β-Glucans are potent inducers of immune function. The present randomized, double blind, two-center, placebo-controlled study was undertaken to explore safety, tolerability and efficacy of soluble β-1,3/1,6-glucan (SBG) as a local treatment of diabetic foot ulcers.

MATERIALS AND METHODS

A total of 60 patients with type 1 or 2 diabetes and lower extremity ulcers (Wagner grade 1-2, Ankle/Brachial Index ≥0.7) received SBG or a comparator product (methylcellulose) locally three times weekly up to 12 weeks in addition to conventional management scheme. A total of 54 patients completed the study.

RESULTS

A tendency for shorter median time to complete healing in the SBG group was observed (36 vs 63 days, P = 0.130). Weekly percentage reduction in ulcer size was significantly higher in the SBG group than in the methylcellulose group between weeks 1-2, 3-4 and 5-6 (P < 0.05). The proportion of ulcers healed by week 12 was also in favor of SBG (59% vs 37%, P = 0.09), with a significantly higher healing incidence in the SBG group at week 8 (44% vs 17%, P = 0.03). SBG was safe and well tolerated. There was a clinically significant difference regarding the incidence of serious adverse events in favor of the SBG treatment.

CONCLUSIONS

Local treatment of diabetic lower extremity ulcers with β-1,3/1,6-polyglucose shows good safety results. This β-glucan preparation shows promising potential as a treatment accelerating cutaneous healing. Further studies are required to confirm this effect. This trial was registered with ClinicalTrials.gov (no. NCT00288392).

Prostaglandin transporter modulates wound healing in diabetes by regulating prostaglandin-induced angiogenesis

Prostaglandin transporter (PGT) mediates prostaglandin (PG) catabolism and PG signal termination. The prostanoid PGE(2), which induces angiogenesis and vasodilation, is diminished in diabetic skin, suggesting that PGT up-regulation could be important in wound healing deficiency, typified by diabetic foot ulcer. We hypothesized that up-regulation of PGT in hyperglycemia could contribute to weakened PGE(2) signaling, leading to impaired angiogenesis and wound healing. In human dermal microvascular endothelial cells (HDMECs), exposure to hyperglycemia increased PGT expression and activity up to threefold, accompanied by reduced levels of PGE(2). Hyperglycemia reduced HDMEC migration by 50% and abolished tube formation. Deficits in PGE(2) expression, HDMEC migration, and tube formation could be corrected by treatment with the PGT inhibitor T26A, consistent with the idea that PGT hyperactivity is responsible for impairments in angiogenesis mediated by PG signaling. In vivo, PGT expression was profoundly induced in diabetes and by wounding, correlating with diminished levels of proangiogenic factors PGE(2) and VEGF in cutaneous wounds of diabetic mice. Pharmacological inhibition of PGT corrected these deficits. PGT inhibition shortened cutaneous wound closure time in diabetic mice from 22 to 16 days. This effect was associated with increased proliferation, re-epithelialization, neovascularization, and blood flow. These data provide evidence that hyperglycemia enhances PGT expression and activity, leading to diminished angiogenic signaling, a possible key mechanism underlying defective wound healing in diabetes.

Polymer-Based Nitric Oxide Therapies: Recent Insights for Biomedical Applications

Since the discovery of nitric oxide (NO) in the 1980s, this cellular messenger has been shown to participate in diverse biological processes such as cardiovascular homeostasis, immune response, wound healing, bone metabolism, and neurotransmission. Its beneficial effects have prompted increased research in the past two decades, with a focus on the development of materials that can locally release NO. However, significant limitations arise when applying these materials to biomedical applications. This Feature Article focuses on the development of NO-releasing and NO-generating polymeric materials (2006-2011) with emphasis on recent in vivo applications. Results are compared and discussed in terms of NO dose, release kinetics, and biological effects, in order to provide a foundation to design and evaluate new NO therapies.

Avaliação de sintomas depressivos em pessoas com diabetes mellitus e pé ulcerado

OBJETIVO: Avaliar a intensidade de sintomas de depressão nos pacientes diabéticos com úlceras no pé. MÉTODOS: Estudo exploratório, descritivo, analítico e transversal, realizado no ambulatório de feridas de um hospital público, de Sorocaba/SP. Participaram 50 pacientes com diabetes mellitus e pé ulcerado. Para mensurar a intensidade dos sintomas de depressão foi utilizado o inventário de Avaliação de Depressão de Beck. RESULTADOS: Dos 50 pacientes avaliados, 41 apresentavam algum grau de sintoma depressivo, sendo que 32 (64%) com depressão moderada, apresentando sintomas de autodepreciação, tristeza, distorção da imagem corporal e diminuição da libido. CONCLUSÃO: Pacientes diabéticos com pé ulcerado apresentaram graus variados de sintomas depressivos.

Dysregulation of monocyte/macrophage phenotype in wounds of diabetic mice

The hypothesis of this study was that cells of the monocyte/macrophage lineage (Mo/Mp) exhibit an impaired transition from pro-inflammatory to pro-healing phenotypes in wounds of diabetic mice, which contributes to deficient healing. Mo/Mp isolated from excisional wounds in non-diabetic db/+ mice exhibited a pro-inflammatory phenotype on day 5 post-injury, with high level expression of the pro-inflammatory molecules interleukin-1β, matrix metalloprotease-9 and inducible nitric oxide synthase. Wound Mo/Mp exhibited a less inflammatory phenotype on day 10 post-injury, with decreased expression of the pro-inflammatory molecules and increased expression of the alternative activation markers CD206 and CD36. In contrast, in db/db mice, the pro-inflammatory phenotype persisted through day 10 post-injury and was associated with reduced expression of insulin-like growth factor-1, transforming growth factor-β1 and vascular endothelial growth factor. Reduced levels of these growth factors in wounds of db/db mice may have contributed to impaired wound closure, reduced granulation tissue formation, angiogenesis and collagen deposition. The persistent pro-inflammatory wound Mo/Mp phenotype in db/db mice may have resulted from elevated levels of pro-inflammatory interleukin-1β and interferon-γ and reduced levels of anti-inflammatory interleukin-10 in the wound environment. Our findings are consistent with the hypothesis that dysregulation of Mo/Mp phenotypes contributes to impaired healing of diabetic wounds.

A parallel open-label trial to evaluate microbial cellulose wound dressing in the treatment of diabetic foot ulcers

The purpose of this study was to compare the rate of wound healing in diabetic foot ulcers (DFU) using either a microbial cellulose (MC) wound dressing or Xeroform™ Petrolatum gauze. In a parallel, open-label trial in which the primary outcome was the rate of wound healing and the time to wound closure, 15 ulcers in type II diabetic patients received an MC dressing. Wounds in 19 control patients with type II diabetes were treated with a Xeroform gauze dressing. All wounds were non infected, Wagner stage II or III and received standard care including debridement, non weight bearing limb support and weekly wound evaluation. The mean time to heal in the MC (±SE) treated group was 32 days ± 2.5 and for controls it was 48 days ± 4.7 (P < 0.01). The rate of weekly wound closure (mean ± SE) was 1.7 times faster in the MC-treated group (cellulose treated, -5.04% per week ± 0.38 versus control, -2.93% per week ± 0.19), (P < 0.001). Among covariants tested by univariate regression, only the original wound area correlated with the time to wound closure (P < 0.001). In conclusion, with the provision of current standards of care, the application of an MC dressing to a diabetic ulcer may enhance the rate of wound healing and shorten the time course of epithelisation.