Delayed Healing of Sickle Cell Ulcers Is due to Impaired Angiogenesis and CXCL12 Secretion in Skin Wounds

Controversies in the pathophysiology of leg ulcers in sickle cell disease

Patients with sickle cell disease (SCD) often experience painful vaso-occlusive crises and chronic haemolytic anaemia, as well as various acute and chronic complications, such as leg ulcers. Leg ulcers are characterized by their unpredictability, debilitating pain and prolonged healing process. The pathophysiology of SCD leg ulcers is not well defined. Known risk factors include male gender, poor social conditions, malnutrition and a lack of compression therapy when oedema occurs. Leg ulcers typically start with spontaneous pain, followed by induration, hyperpigmentation, blister formation and destruction of the epidermis. SCD is characterized by chronic haemolysis, increased oxidative stress and decreased nitric oxide bioavailability, which promote ischaemia and inflammation and consequently impair vascular function in the skin. This cutaneous vasculopathy, coupled with venostasis around the ankle, creates an ideal environment for local vaso-occlusive crises, which can result in the development of leg ulcers that resemble arterial ulcers. Following the development of the ulcer, healing is hindered as a result of factors commonly observed in venous ulceration, including venous insufficiency, oedema and impaired angiogenesis. All of these factors are modulated by genetic factors. However, our current understanding of these genetic factors remains limited and does not yet enable us to accurately predict ulceration susceptibility.

Application of Deferoxamine in Tissue Regeneration Attributed to Promoted Angiogenesis

Deferoxamine, an iron chelator used to treat diseases caused by excess iron, has had a Food and Drug Administration-approved status for many years. A large number of studies have confirmed that deferoxamine can reduce inflammatory response and promote angiogenesis. Blood vessels play a crucial role in sustaining vital life by facilitating the delivery of immune cells, oxygen, and nutrients, as well as eliminating waste products generated during cellular metabolism. Dysfunction in blood vessels may contribute significantly to the development of life-threatening diseases. Anti-angiogenesis therapy and pro-angiogenesis/angiogenesis strategies have been frequently recommended for various diseases. Herein, we describe the mechanism by which deferoxamine promotes angiogenesis and summarize its application in chronic wounds, bone repair, and diseases of the respiratory system. Furthermore, we discuss the drug delivery system of deferoxamine for treating various diseases, providing constructive ideas and inspiration for the development of new treatment strategies.

Mouse models of sickle cell disease: Imperfect and yet very informative

The root cause of sickle cell disease (SCD) has been known for nearly a century, however, few therapies to treat the disease are available. Over several decades of work, with advances in gene editing technology and after several iterations of mice with differing genotype/phenotype relationships, researchers have developed humanized SCD mouse models. However, while a large body of preclinical studies has led to huge gains in basic science knowledge about SCD in mice, this knowledge has not led to the development of effective therapies to treat SCD-related complications in humans, thus leading to frustration with the paucity of translational progress in the SCD field. The use of mouse models to study human diseases is based on the genetic and phenotypic similarities between mouse and humans (face validity). The Berkeley and Townes SCD mice express only human globin chains and no mouse hemoglobin. With this genetic composition, these models present many phenotypic similarities, but also significant discrepancies that should be considered when interpreting preclinical studies results. Reviewing genetic and phenotypic similarities and discrepancies and examining studies that have translated to humans and those that have not, offer a better perspective of construct, face, and predictive validities of humanized SCD mouse models.

Contribution of fetal microchimeric cells to maternal wound healing in sickle cell ulcers

Leg ulcers are a major complication of sickle cell disease (SCD). They are particularly challenging to treat and innovative therapies are needed. We previously showed that the healing of SCD ulcers is delayed because of decreased angiogenesis. During pregnancy, fetal microchimeric cells (FMC) transferred to the mother are recruited to maternal wounds and improve angiogenesis. After delivery, FMC persist in maternal bone marrow for decades. Here, we investigated whether fetal cells could also improve SCD ulcers in the post-partum setting. We found that skin healing was similarly improved in post-partum mice and in pregnant mice, through increased proliferation and angiogenesis. In a SCD mouse model that recapitulates refractory SCD ulcers, we showed that the ulcers of post-partum SCD mice healed more quickly than those of virgin mice. This was associated with the recruitment of fetal cells in maternal wounds where they harbored markers of leukocytes and endothelial cells. In a retrospective cohort of SCD patients, using several parameters we found that SCD women who had ever had a baby had less of a burden related to leg ulcers compared to nulliparous women. Taken together, these results indicate that healing capacities of FMC are maintained long after delivery and may be exploited to promote wound healing in post-partum SCD patients.

Phenotypic characterisation and associations of leg ulcers in adult sickle cell patients

Sickle leg ulcer (SLU) occurs as a result chronic occlusion of the vasculature with consequent necrosis of the skin and subcutaneous tissue usually in proximity of the malleoli. The description of clinical associations and the simultaneous occurrence of SLU and other complications of SCD compared to the non-SLU patients was the aim of this work. A total of 272 (60.8% males and 39.2% females) patients were captured during this time period out of which 68 (51 males and 17 females) had SLU out of whom 20 patients had bilateral leg ulcers. Prevalence of SLU was 25% and the median age of patients was 25 years, frequency of crisis 2 per annum and 44 (74.6%) had been transfused in the past. Median Hb of the group was 7.6 g/dl and 25% had values lower than 6.5. The occurrence of other complications in SLU patients was as follows; 10 had AVN, 9 priapism, 8 had osteomyelitis, 6 nephropathy, stroke 2, osteoarthritis 4 and cholelithiasis 4. There was a significant relationship between the occurrence of SLU and gender of the patient being more in 67males-Likelihood ratio 4.610 (p = 0.032) and the occurrence of pulmonary hypertension-Likelihood ratio 4.762 (p = 0.029). There was no significant association between the occurrence of SLU and other complications of SCD. Leg ulcer patients have a median age of 25 years with a prevalence of 25% but do not necessarily show other features of severe disease phenotypes. SLU patients were more likely to develop pulmonary hypertension. Further studies on impact of environmental factors on the occurrence of SLU are needed to further evaluate its aetiology.

SDF-1α Gene-Activated Collagen Scaffold Restores Pro-Angiogenic Wound Healing Features in Human Diabetic Adipose-Derived Stem Cells

Non-healing diabetic foot ulcers (DFUs) can lead to leg amputation in diabetic patients. Autologous stem cell therapy holds some potential to solve this problem; however, diabetic stem cells are relatively dysfunctional and restrictive in their wound healing abilities. This study sought to explore if a novel collagen-chondroitin sulfate (coll-CS) scaffold, functionalized with polyplex nanoparticles carrying the gene encoding for stromal-derived factor-1 alpha (SDF-1α gene-activated scaffold), can enhance the regenerative functionality of human diabetic adipose-derived stem cells (ADSCs). We assessed the impact of the gene-activated scaffold on diabetic ADSCs by comparing their response against healthy ADSCs cultured on a gene-free scaffold over two weeks. Overall, we found that the gene-activated scaffold could restore the pro-angiogenic regenerative response in the human diabetic ADSCs similar to the healthy ADSCs on the gene-free scaffold. Gene and protein expression analysis revealed that the gene-activated scaffold induced the overexpression of SDF-1α in diabetic ADSCs and engaged the receptor CXCR7, causing downstream β-arrestin signaling, as effectively as the transfected healthy ADSCs. The transfected diabetic ADSCs also exhibited pro-wound healing features characterized by active matrix remodeling of the provisional fibronectin matrix and basement membrane protein collagen IV. The gene-activated scaffold also induced a controlled pro-healing response in the healthy ADSCs by disabling early developmental factors signaling while promoting the expression of tissue remodeling components. Conclusively, we show that the SDF-1α gene-activated scaffold can overcome the deficiencies associated with diabetic ADSCs, paving the way for autologous stem cell therapies combined with novel biomaterials to treat DFUs.

Mixed Bullous-Eczematous Contact Dermatitis From a Black Henna Tattoo in an African American Female With Sickle Cell Disease With Post-Dermatitis Pain

Traditionally practiced in East Asian and Southeast Asian countries, Henna tattooing has gained western popularity in creating temporary decorative patterns on the skin. Derived from the Lawsonia inermis shrub prevalent in Asia/Southeast Asia, the leaves of this plant are ground to create a paste with a brown pigment commonly called Mehndi or Henna which have deep-rooted cultural values/practices. The pure organic form of these compounds has few reported side effects. However, with gaining western popularity, synthetic additives to the natural paste to create color variation, shorten application times, and increase shelf-life have led to an increase in the incidence of adverse reactions. Namely attributed to synthetic compounds like para-phenylenediamine (PPD) or para-toluylenediamine, this synthetic type of mixture is called black henna. Although multiple types of adverse reactions with black henna have been documented as an eczematous type of reaction, few if any cases of adverse reactions of black henna affecting patients with sickle cell disease (SCD) have been documented. In this case, we aim to present an atypical mixed bullous-eczematous contact dermatitis reaction secondary to a PPD containing black henna dye applied to the skin of a patient with homozygous SCD. We intend to raise awareness of the deleterious cosmetic sequelae and chronic post-dermatitis pain manifestations which may arise in patients with SCD, as the popularity of black henna tattooing grows in the United States where SCD is one of the most prevalent hemoglobinopathies amongst black Americans.

Leg Ulcers in Sickle-Cell Disease: Treatment Update

Significance: Sickle-cell leg ulcers (SCLUs) are a severe, chronic, and recurrent complication of sickle-cell disease (SCD). There are no official recommendations for treatment. Recent Advances: Only a few studies with a high level of evidence have been conducted to evaluate treatment of SCLUs. However, several studies have been conducted with a high level of evidence to evaluate the efficacy of treatments in venous leg ulcers, and SCLUs could benefit from these treatments, especially when a venous incompetence or an edema is associated. Pathophysiology of SCLUs includes a vasculopathy related to chronic hemolysis and an endothelial dysfunction, which could be therapeutic approaches to SCLU treatment. Critical Issues: Therapeutic approaches to SCLUs can target SCD on the one hand and skin healing and associated aggravating factors on the other. A review of the literature found only case series and six randomized controlled trials; some offered encouraging results, but most had serious biases. Clinical trials specifically targeting SCLUs are difficult to realize because of the small number of affected patients, in comparison with patients with leg ulcers from other causes. Future Direction: Treating SCLUs remains a challenge. Data in the literature are currently insufficient to offer clear treatment guidelines because of several biases in controlled studies. New studies are under way to assess the efficacy of topical treatments and describe the microbiome of SCLUs. Prevention of SCLU recurrence should be assessed in future clinical trials because the high risk of recurrence is an unsolved critical issue.

Sickle cell disease induces resistance to cutaneous carcinogenesis

Background

While skin carcinomas are reported in chronic ulcers and in patients treated with hydroxyurea (HU) for myeloproliferative neoplasms, no skin carcinoma has been reported in patients with sickle cell disease (SCD), presenting chronic skin ulcers or treated with HU. The objective was to estimate the risk of cutaneous malignant transformation in SCD patients with prolonged leg ulcers or under HU therapy.

Results

In this cross-sectional study, the cohort consisted of 1543 patients. In the first series, 29 patients presented a total of 53 ulcers lasting more than two years. The median age was 35 ± 8.4 years old. The median duration for a single ulcer was 9.2 ± 7 years. None of the examined ulcers showed any suspicious area of malignant transformation. In the second series, 187 patients treated with HU for more than two years were identified. The median age was 31.3 ± 9.9 years old. The median duration of treatment with HU was 6 ± 3.2 years. No skin carcinoma or actinic keratosis was recorded.

Conclusions

This study showed that skin carcinogenesis did not occur in our series of SCD patients exposed to transforming events such as long term HU treatment or prolonged leg ulcers.

Impact of Sickle Cell Anemia on Inpatient Morbidity After Spinal Fusion

STUDY DESIGN

A retrospective study.

OBJECTIVE

To determine the impact of sickle cell anemia on perioperative outcomes and resource utilization in elective spinal fusion surgery.

SUMMARY OF BACKGROUND DATA

Sickle cell anemia has been identified as an important surgical risk factor in otolaryngology, cardiothoracic surgery, general surgery, and total joint arthroplasty. However, the impact of sickle cell anemia on elective spine surgery is unknown.

METHODS

Hospitalizations for elective spinal fusion surgery between the years of 2001-2014 from the US National Inpatient Sample were identified using ICD-9-CM codes and patients were grouped into those with and without sickle cell anemia. The main outcome measures were in-hospital neurological, respiratory, cardiac, gastrointestinal, renal and urinary, pulmonary embolism, and wound-related complications and mortality. Length of stay and inpatient costs were also collected. Multivariable logistic regressions were conducted to compare the in-hospital outcomes of patients undergoing elective spinal fusion with or without sickle cell anemia.

RESULTS

From a total of 4,542,719 patients undergoing elective spinal fusions from 2001 to 2014, 456 sickle cell disease patients were identified. Sickle cell anemia is a significant independent predictor for pulmonary embolism [odds ratio (OR)=7.37; confidence interval (CI), 4.27-12.71; P<0.001], respiratory complications (OR=2.36; CI, 1.63-3.42; P<0.001), wound complications (OR=3.84; CI, 2.72-5.44; P<0.001), and overall inpatient complications (OR=2.58; CI, 2.05-3.25; P<0.001). Sickle cell anemia patients also have significantly longer length of stay (7.0 vs. 3.8 d; P<0.001) and higher inpatient costs ($20,794 vs. $17,608 P<0.05).

CONCLUSIONS

Sickle cell anemia is associated with increased risk of perioperative complications and greater health care resource utilization. Sickle cell anemia patients undergoing spinal fusion surgeries should be counseled on these increased risks. Moreover, current strategies for perioperative management of sickle cell anemia patients undergoing spinal fusion surgery need to be improved.

Investigating the potential of the secretome of mesenchymal stem cells derived from sickle cell disease patients

Sickle cell disease (SCD) is a monogenic red cell disorder associated with multiple vascular complications, microvessel injury and wound-healing deficiency. Although stem cell transplantation with bone marrow-derived mesenchymal stem cells (BMSC) can promote wound healing and tissue repair in SCD patients, therapeutic efficacy is largely dependent on the paracrine activity of the implanted BM stromal cells. Since in vitro expansion and culture conditions are known to modulate the innate characteristics of BMSCs, the present study investigated the effects of normoxic and hypoxic cell-culture preconditioning on the BMSC secretome, in addition to the expression of paracrine molecules that induce angiogenesis and skin regeneration. BMSCs derived from SCD patients were submitted to culturing under normoxic (norCM) and hypoxic (hypoCM) conditions. We found that hypoxically conditioned cells presented increased expression and secretion of several well-characterized trophic growth factors (VEGF, IL8, MCP-1, ANG) directly linked to angiogenesis and tissue repair. The hypoCM secretome presented stronger angiogenic potential than norCM, both in vitro and in vivo, as evidenced by HUVEC proliferation, survival, migration, sprouting formation and in vivo angiogenesis. After local application in a murine wound-healing model, HypoCM showed significantly improved wound closure, as well as enhanced neovascularization in comparison to untreated controls. In sum, the secretome of hypoxia-preconditioned BMSC has increased expression of trophic factors involved in angiogenesis and skin regeneration. Considering that these preconditioned media are easily obtainable, this strategy represents an alternative to stem cell transplantation and could form the basis of novel therapies for vascular regeneration and wound healing in individuals with sickle cell disease.

Cutaneous Wound Healing in Diabetic Mice Is Improved by Topical Mineralocorticoid Receptor Blockade

Skin ulcers resulting from impaired wound healing are a serious complication of diabetes. Unresolved inflammation, associated with the dysregulation of both the phenotype and function of macrophages, is involved in the poor healing of diabetic wounds. Here, we report that topical pharmacological inhibition of the mineralocorticoid receptor (MR) by canrenoate or MR small interfering RNA can resolve inflammation to improve delayed skin wound healing in diabetic mouse models; importantly, wounds from normal mice are unaffected. The beneficial effect of canrenoate is associated with an increased ratio of anti-inflammatory M2 macrophages to proinflammatory M1 macrophages in diabetic wounds. Furthermore, we show that MR blockade leads to downregulation of the MR target, LCN2, which may facilitate macrophage polarization toward the M2 phenotype and improve impaired angiogenesis in diabetic wounds. Indeed, diabetic LCN2-deficient mice showed improved wound healing associated with macrophage M2 polarization and angiogenesis. In addition, recombinant LCN2 protein prevented IL-4-induced macrophage switch from M1 to M2 phenotype. In conclusion, topical MR blockade accelerates skin wound healing in diabetic mice via LCN2 reduction, M2 macrophage polarization, prevention of inflammation, and induction of angiogenesis.

Evaluation of the expression of the stromal cell-derived factor-1 alpha (CXCL 12) in psoriatic patients after treatment with Methotrexate

BACKGROUND

CXCL12 has an important role in skin homeostasis and inflammation.

OBJECTIVE

In this work, the expression of CXCL12 was evaluated in psoriasis vulgaris, psoriatic arthritis (PsA) patients in relation to disease activity and methotrexate (MTX) therapy.

METHODS

Skin biopsies were obtained from 10 psoriasis vulgaris patients, 10 PsA patients, and 20 controls. The biopsies were repeated 6 weeks after MTX therapy. The biopsies were stained immunohistochemically by stromal dermal factor 1 alpha (CXCL 12) antibody.

RESULTS

Psoriatic arthritis showed significantly more expression of CXCL 12 than psoriasis vulgaris patients before treatment but not after treatment. There was significant decrease in CXCL 12 expression in the keratinocytes of psoriasis vulgaris patients after MTX therapy than before treatment, P-value was 0.009. There was no significant difference between pre- and post-treatment in the CXCL 12 expression of keratinocytes of PsA patients, P-value was 0.093. The percentage decrease of PASI score after treatment showed a moderate correlation with the percentage decrease of CXCL12 expression of the keratinocytes of the total psoriasis patients, r = 0.484, P-value was 0.015.

CONCLUSION

CXCL12 might be involved in the progression of psoriasis vulgaris to PsA. MTX therapy downregulated the expression of CXCL12 of the keratinocytes of psoriasis patients. This downregulation was paralleled by decrease in the PASI score. CXCL12 can be used as a biological marker of disease severity of psoriasis patients.

Biologics in Microangiopathic Wounds

In the last decades the possibility to diagnose a skin ulcer has greatly improved. We learnt that a consistent percentage of nonhealing ulcers may be caused by a microangiopathic disorder that has not been properly investigated and cured. Pathogenetically, we can distinguish 2 main groups: (1) ulcers due to inflammatory microangiopathy, mainly including cutaneous small and medium vessel vasculitis, pyoderma gangrenosum, and connective tissue diseases, and (2) ulcers due to occlusive microangiopathy. The group of microangiopathic occlusive ulcers is more heterogeneous and includes different disorders ranging from livedo vasculopathy to calciphylaxis, hydroxyurea-induced ulcers, antiphospholipid antibodies ulcers, and various other types. These conditions can induce thromboses or anatomo-functional occlusion of cutaneous microvessels. Despite different physiopathologic mechanisms, the ulcer resulting from a primitive microangiopathy may receive basic treatments that are in the complex similar to other pathogenetically different wounds, including MOIST-based local therapy and elastic compression when it is not contraindicated. Persistent inflammatory processes are increasingly demonstrated as responsible for the chronicity of many skin ulcers. New data concerning the biological phases of wound healing and the molecules that play crucial roles in this process suggested the use of new specific therapies. Some of them such as growth factors and platelet-rich plasma are prevalently used as topical biologic agents with variable benefits. In recent years, a new class of systemic anti-inflammatory molecules, better known as biologic drugs, have been introduced in the cure of chronic inflammatory diseases that can induce microangiopathic injuries and ulcerative complication. They enlarged the therapeutic options in case of nonresponder microangiopathic ulcers and could represent a future model of “pathogenetically based” therapy of skin ulcers.

Lumbar sympathectomy regulates vascular cell turnover in rat hindfoot plantar skin

BACKGROUND

Sympathetic denervation and impaired angiogenesis cause skin diseases. However, the relationship between the sympathetic nervous system and vascular cell turnover in normal skin remains unclear.

OBJECTIVE

To determine the effects of sympathetic denervation on vascular cell turnover in normal skin.

METHODS

Rats underwent bilateral L2-4 sympathetic trunk resection (sympathectomy group) or sham operation (control). Hindfoot plantar skin was analyzed 2 weeks and 3 months postoperatively.

RESULTS

Mural cell marker (α-smooth muscle actin; p < 0.001, and desmin; p = 0.047) expression decreased 2 weeks after sympathectomy, but recovered 3 months after sympathectomy (p > 0.05). CD31 levels were lower in the experimental group than in the control group at 2 weeks (p = 0.009), but not at 3 months. Von Willebrand factor, vascular endothelial growth factor, and angiopoietin-2 expression were not significantly different between the groups (p > 0.05). Angiopoietin-1 expression levels were higher in the experimental group than in the control group at 2 weeks (p = 0.035), but not at 3 months.

CONCLUSIONS

Lumbar sympathectomy regulates vascular cell turnover in rat hindfoot plantar skin by inhibiting mural cell proliferation and increasing angiopoietin-1 expression. Sympathetic nerves therefore play an important role in plantar skin vascular cell turnover.

Low-dose methotrexate in sickle-cell disease: a pilot study with rationale borrowed from rheumatoid arthritis

Background

Inflammation is a major feature of sickle cell disease (SCD). Low-dose methotrexate (MTX) has long been used in chronic inflammatory diseases. This pilot study examined the MTX effect on acute vaso-occlusive pain crises (VOC) in SCD patients.

Methods

Fourteen adults on hydroxyurea with severe and refractory VOC received one intramuscular injection of 10 mg of MTX per week for 12 weeks. A single weekly dose of 5 mg of leucovorin was administered orally 48 h after each MTX injection. The primary outcome was reduction in number/intensity of acute pain episodes. The secondary outcomes were improvement of quality of life (QOL) and reduction of the inflammatory status.

Results

MTX did not significantly change the median VOC frequency (12 before vs 10.5 during treatment, P = 0.6240) or the median McGill pain index (45 at week 0 vs 39.5 at week 12, P = 0.9311). However, there was a decrease of ≥50% in chronic pain resulting from avascular osteonecrosis (AVN) in 5 out of 7 patients with radiologic evidence of AVN, with the perception of longer pain-free periods. There was a 44.4% median gain in physical function in the SF-36 QOL questionnaire (P = 0.0198). MTX treatment up-regulated two C-X-C motif chemokines (CXCL), CXCL10 (P = 0.0463) and CXCL12 (P < 0.0001), without significant effect on 14 additional plasma inflammatory markers. Adverse events: One individual had fever of unknown origin. Respiratory tract infections were recorded in five patients. Among the latter, one also had dengue fever and another had a central venous line infection and died of pneumonia and septic shock. Three patients with previous history of hydroxyurea-induced hematological toxicity developed low blood platelet counts while receiving simultaneously MTX and hydroxyurea.

Conclusions

Although MTX did not reduce acute VOC frequency/intensity, it decreased chronic pain and led to QOL improvement.

Trial registrationhttp://www.who.int/ictrp/en/ and http://www.ensaiosclinicos.gov.br, RBR-2s9xvn, 19 December 2016, retrospectively registered

Electronic supplementary material

The online version of this article (doi:10.1186/s40164-017-0078-1) contains supplementary material, which is available to authorized users.

IL-27 Facilitates Skin Wound Healing through Induction of Epidermal Proliferation and Host Defense

Skin wound repair requires a coordinated program of epithelial cell proliferation and differentiation as well as resistance to invading microbes. However, the factors that trigger epithelial cell proliferation in this inflammatory process are incompletely understood. In this study, we demonstrate that IL-27 is rapidly and transiently produced by CD301b⁺ cells in the skin after injury. The functional role of IL-27 and CD301b⁺ cells is demonstrated by the finding that CD301b-depleted mice exhibit delayed wound closure in vivo, which could be rescued by topical IL-27 treatment. Furthermore, genetic ablation of the IL-27 receptor (Il27Ra^−/−) attenuates wound healing, suggesting an essential role for IL-27 signaling in skin regeneration in vivo. Mechanistically, IL-27 feeds back on keratinocytes to stimulate cell proliferation and re-epithelialization in the skin, whereas IL-27 leads to suppression of keratinocyte terminal differentiation. Finally, we identify that IL-27 potently increases expression of the antiviral oligoadenylate synthetase 2, but does not affect expression of antibacterial human beta defensin 2 or regenerating islet-derived protein 3-alpha. Together, our data suggest a previously unrecognized role for IL-27 in regulating epithelial cell proliferation and antiviral host defense during the normal wound healing response.