Vasculopathy, inflammation, and blood flow in leg ulcers of patients with sickle cell anemia

Wounds resulting from non-malignant haematological disease: a case series

A proactive and systemic approach is imperative to preventing wounds due to disorders of non-malignant haematologic disease. Here, the authors provide several examples of patients with either a known history or acute diagnosis of a coagulation disorder with the aim of reviewing potential cutaneous injuries as well as diagnosis and treatment. A description of the wound and treatment course along with recommendations where appropriate are presented. The article serves as a general review for health professionals who may encounter patients with this disorder and who are involved in treatment decisions. After reviewing the article, the practitioner will be able to identify cutaneous injuries that may be secondary to an underlying haematological disorder, review the diagnosis and treatment recommended, and understand the need for a multidisciplinary approach to patient care.

Leg Ulcers in Sickle Cell Disease: A Multifactorial Analysis Highlights the Hemolytic Profile

Sickle cell disease (SCD) is characterized by the presence of the variant S hemoglobin (HbS). The homozygous genotype (HbSS) is sickle cell anemia (SCA), while the double heterozygous of HbS and HbC (HbSC) is defined as SC hemoglobinopathy. The pathophysiology is based on chronic hemolysis, inflammation, endothelial dysfunction, and vaso-occlusion, which results in vasculopathy and serious clinical manifestations. Sickle leg ulcers (SLUs) are cutaneous lesions around the malleoli frequent in 20% of Brazilian patients with SCD. SLUs present a variable clinical and laboratory pattern modulated by several characteristics that are not fully understood. Hence, this study aimed to investigate laboratory biomarkers and genetic and clinical parameters associated with the development of SLUs. This descriptive cross-sectional study included 69 SCD patients, 52 without SLU (SLU-) and 17 with active or previous SLU history (SLU+). The results showed a higher incidence of SLU in SCA patients and there was no observed association of α-3.7 Kb thalassemia in SLU occurrence. Alterations in NO metabolism and hemolysis were associated with clinical evolution and severity of SLU, in addition to hemolysis modulating the etiology and recurrence of SLU. Our multifactorial analyses demonstrate and extend the role of hemolysis driving the pathophysiological mechanism of SLU.

The impact of MCP1-2518A/G and CCR2-V64I genetic polymorphisms in Egyptian sickle cell disease patients

BACKGROUND

Sickle cell disease (SCD) is an inherited genetic disorders of hemoglobin that causes multisystem morbidity. The pathophysiology of SCD is complex and includes HbS polymerization/sickling, hemolysis, endothelial dysfunction and inflammation. Chemokines are proteins playing an important role in the inflammation process and could be involved the context of pro-inflammatory SCD. Some chemokine polymorphism were found to be associated with clinical complication in SCD.

AIM OF THE STUDY

Was to explore the frequency and the possible effect of Monocyte Chemo-attractant Protein 1-2518A/G (MCP1-2518A/G) and Chemokine Receptor 2-V64I (CCR2-V64I) genetic polymorphisms on clinical and laboratory disease-related variables in Egyptian Sickle cell disease patients.

PATIENTS AND METHODS

Genotyping of the two genes were performed by PCR-RFLP technique for 80 SCD patients as well as 50 healthy control group.

RESULTS

The study revealed that the MCP1-2518 polymorphic genotypes (AG & GG) showed no statistically significant difference in the distribution of the polymorphic genotypes between SCD patients and the controls (p = 0.164). While a significantly higher frequency of the mutant variants CCR2-V64I GA/AA among SCD patients than the control subjects were found (p = 0.032). Regarding the clinic-pathological features, the frequency of recurrent infections, vaso-occlusive crisis, severe vaso-occlusive crisis and number of hospitalization/year were higher in patients harbouring the MCP1-2518A/G and CCR2-V64I polymorphic genotypes than the wild genotype, and gall bladder complications were higher in MCP1-2518 G allele patients, whereas surgical splenectomy were higher in CCR2-V64I A allele patients (p < 0.05).

IN CONCLUSION

MCP1-2518A/G and CCR2-V64I genetic polymorphisms may influence the clinical severity of sickle cell disease.

Antithrombin-III mitigates thrombin-mediated endothelial cell contraction and sickle red blood cell adhesion in microscale flow

Individuals with sickle cell disease (SCD) have persistently elevated thrombin generation that results in a state of systemic hypercoagulability. Antithrombin‐III (ATIII), an endogenous serine protease inhibitor, inhibits several enzymes in the coagulation cascade, including thrombin. Here, we utilize a biomimetic microfluidic device to model the morphology and adhesive properties of endothelial cells (ECs) activated by thrombin and examine the efficacy of ATIII in mitigating the adhesion of SCD patient‐derived red blood cells (RBCs) and EC retraction. Microfluidic devices were fabricated, seeded with ECs, and incubated under physiological shear stress. Cells were then activated with thrombin with or without an ATIII pretreatment. Blood samples from subjects with normal haemoglobin (HbAA) and subjects with homozygous SCD (HbSS) were used to examine RBC adhesion to ECs. Endothelial cell surface adhesion molecule expression and confluency in response to thrombin and ATIII treatments were also evaluated. We found that ATIII pretreatment of ECs reduced HbSS RBC adhesion to thrombin‐activated endothelium. Furthermore, ATIII mitigated cellular contraction and reduced surface expression of von Willebrand factor and vascular cell adhesion molecule‐1 (VCAM‐1) mediated by thrombin. Our findings suggest that, by attenuating thrombin‐mediated EC damage and RBC adhesion to endothelium, ATIII may alleviate the thromboinflammatory manifestations of SCD.

Abnormal Lower Extremity Hemodynamics at Doppler US in Children with Sickle Cell Anemia

Background Children with sickle cell anemia (SCA) are predisposed to developing leg ulcers in early adolescence; however, the underlying physiologic mechanisms are not well understood, which hinders the development of prophylactic antiulcer interventions. Purpose To determine if occlusive arterial disease or abnormal hemodynamics exist in the lower limb peripheral arteries of children with SCA. Materials and Methods This was a prospective cross-sectional study conducted between July 2020 and May 2021. Two groups of participants were enrolled: children with SCA and healthy controls. Each child had their anthropometric measurements taken, followed by B-mode, color Doppler, and spectral Doppler US evaluation of the distal anterior and posterior tibial arteries. Ankle-brachial index evaluation was also performed. Hemodynamic values were compared between children with SCA and healthy controls, with statistical significance set at the P < .05 level. Results Forty-five children with SCA (mean age, 9.5 years ± 3.7 [SD]; 26 boys) and 45 healthy controls (mean age, 9.3 years ± 3.8; 25 boys) were evaluated. Children with SCA had higher peak systolic velocities, end-diastolic velocities, and blood volume flow in their distal anterior and posterior tibial arteries compared with the healthy participants (P < .001 across all 12 measurements). Children with SCA also had lower resistive index and pulsatility index values compared with healthy controls in at least one of the anterior and posterior tibial arteries bilaterally. Monophasic spectral patterns were exclusively observed in participants with SCA. The ankle-brachial index values for the participants with SCA (mean, 1.09 ± 0.08) and healthy participants (mean, 1.06 ± 0.02) were within normal range. Conclusion Abnormal peripheral hemodynamic characteristics were found in the lower limbs of children with sickle cell anemia. No evidence of occlusive peripheral artery disease was present. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Paltiel in this issue.

Healing outcomes and predictors among patients with venous leg ulcers treated with compression therapy

OBJECTIVE

This study aimed to compare the healing outcomes between three types of compression therapy-two-layer bandage (2LB), four-layer bandage (4LB), and compression stockings, and to identify the predictors of venous leg ulcer (VLU) healing.

METHOD

A retrospective review of the medical records of patients diagnosed with VLU between 2011 and 2016 in Singapore was conducted. Univariate and multivariate analyses were done between healed and unhealed VLU patients at three and six months, based on potential factors, ranging from demographic profile to comorbidities and treatment-related variables.

RESULTS

Data from 377 patients' medical records were analysed. The healing rates with the three types of compression system, 4LB, 2LB and compression stockings, were 22.3%, 34.9% and 8.7% respectively at three months; at six months they were 44.2%, 41.9% and 34.8% respectively. Patients on 2LB reported a significantly higher proportion of healed ulcers at three months (p=0.003) but at six months there was no difference in healing rates between the three types of therapy. At three and six months, the duration of compression therapy was found to be an independent predictor of healing (p<0.001).

CONCLUSION

In this study, the 2LB appeared to show the most favourable healing outcome in the short-term but as VLUs persisted beyond the months, the type of compression system used did not make a difference in the healing outcome. Our findings suggested that, as the duration became more prolonged, VLUs became more resistant to healing despite compression therapy. Therefore, it may be necessary for clinicians to consider adjuvant therapies for hard-to-heal ulcers at an earlier stage.

Hydroxyurea and fetal hemoglobin effect on leg ulcers in patients with sickle cell disease

The presence of leg ulcers in individuals with sickle cell disease often represents an early sign of vasculopathy and future end organ damage. Pathophysiological mechanisms of formation and evolution of leg ulcers are poorly understood; nevertheless, HbF has been associated with lower incidence of leg ulcers, while hydroxyurea has been correlated with high risk of leg ulcers. As a result, there is hesitation regarding hydroxyurea use in patients with SCD and leg ulcers. In this study, we aim to define (1) a target of HbF that offers protection against leg ulcer development and (2) the impact of hydroxyurea therapy on leg ulcer prevalence. Our study demonstrated that in order to reduce leg ulcer incidence by one-third, a HbF > 25% is needed, a threshold not commonly reached and maintained in the adult SCD population. Importantly, leg ulcer incidence appears to be independent of HU use (p = 0.50). Our interpretation of this data is that the use of HU in a patient with SCD and leg ulcers should be guided by a careful assessment of risks and benefits of this therapeutic modality.

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.

Common, But Neglected: A Comprehensive Review of Leg Ulcers in Sickle Cell Disease

OBJECTIVE

To compile available evidence to better understand the management of leg ulcers in sickle cell disease (SCD), as well as describe potential therapeutic steps that may be required to improve the quality of life of patients with SCD leg ulcers.

DATA SOURCES

MEDLINE, PubMed, EMBASE, and Web of Science databases.

STUDY SELECTION

A comprehensive search was conducted to retrieve relevant studies using the keywords "sickle cell disease and leg ulcer," "ulcer treatments, diagnosis and sickle cell," and "wound sickle cell." Studies published through July 2020 were included.

DATA EXTRACTION

Two independent authors selected all studies that assessed the relationship between leg ulcer and SCD identified from online databases.

DATA SYNTHESIS

The authors have summarized updated information on pathophysiology (vasculopathy linked to chronic hemolysis and endothelial dysfunction), diagnosis, and available treatment options to unravel the dermohematologic connection between leg ulcers and SCD.

CONCLUSIONS

It is the authors' hope that this detailed discussion of the information available on leg ulcers and SCD will lead to a better appreciation of this clinical problem by the clinicians and researchers and in turn have a long-term positive effect on the quality of life of patients with SCD. Researchers should design new trials considering these insights and potential therapeutic approaches based on current knowledge.

Novel leukocyte-depleted platelet-rich plasma-based skin equivalent as an in vitro model of chronic wounds: a preliminary study

BACKGROUND

Chronic leg ulcerations are associated with Haemoglobin disorders, Type2 Diabetes Mellitus, and long-term venous insufficiency, where poor perfusion and altered metabolism develop into a chronic inflammation that impairs wound closure. Skin equivalent organotypic cultures can be engineered in vitro to study skin biology and wound closure by modelling the specific cellular components of the skin. This study aimed to develop a novel bioactive platelet-rich plasma (PRP) leukocyte depleted scaffold to facilitate the study of common clinical skin wounds in patients with poor chronic skin perfusion and low leukocyte infiltration. A scratch assay was performed on the skin model to mimic two skin wound conditions, an untreated condition and a condition treated with recombinant tumour necrotic factor (rTNF) to imitate the stimulation of an inflammatory state. Gene expression of IL8 and TGFA was analysed in both conditions. Statistical analysis was done through ANOVA and paired student t-test. P < 0.05 was considered significant.

RESULTS

A skin model that consisted of a leukocyte-depleted, platelet-rich plasma scaffold was setup with embedded fibroblasts as dermal equivalents and seeded keratinocytes as multi-layered epidermis. Gene expression levels of IL8 and TGFA were significantly different between the control and scratched conditions (p < 0.001 and p < 0.01 respectively), as well as between the control and treated conditions (p < 0.01 and p < 0.001 respectively). The scratch assay induced IL8 upregulation after 3 h (p < 0.05) which continued to increase up to day 1 (p < 0.05). On the other hand, the administration of TNF led to the downregulation of IL8 (p < 0.01), followed by an upregulation on day 2. IL8 gene expression decreased in the scratched condition after day 1 as the natural healing process took place and was lower than in the treated condition on day 8 (p < 0.05). Both untreated and treated conditions showed a downregulation of TGFA 3 h after scratch when compared with the control condition (p < 0.01). Administration of rTNF showed significant downregulation of TGFA after 24 h when compared with the control (p < 0.01) and treated conditions (p < 0.05).

CONCLUSION

This study suggests that a leukocyte-depleted PRP-based skin equivalent can be a useful model for the in vitro study of chronic skin wounds related to poor skin perfusion.

Vasculo-toxic and pro-inflammatory action of unbound haemoglobin, haem and iron in transfusion-dependent patients with haemolytic anaemias

Increasing evidence suggests that free haem and iron exert vasculo‐toxic and pro‐inflammatory effects by activating endothelial and immune cells. In the present retrospective study, we compared serum samples from transfusion‐dependent patients with β‐thalassaemia major and intermedia, hereditary spherocytosis and sickle cell disease (SCD). Haemolysis, transfusions and ineffective erythropoiesis contribute to haem and iron overload in haemolytic patients. In all cohorts we observed increased systemic haem and iron levels associated with scavenger depletion and toxic ‘free’ species formation. Endothelial dysfunction, oxidative stress and inflammation markers were significantly increased compared to healthy donors. In multivariable logistic regression analysis, oxidative stress markers remained significantly associated with both haem‐ and iron‐related parameters, while soluble vascular cell adhesion molecule 1 (sVCAM‐1), soluble endothelial selectin (sE‐selectin) and tumour necrosis factor α (TNFα) showed the strongest association with haem‐related parameters and soluble intercellular adhesion molecule 1 (sICAM‐1), sVCAM‐1, interleukin 6 (IL‐6) and vascular endothelial growth factor (VEGF) with iron‐related parameters. While hereditary spherocytosis was associated with the highest IL‐6 and TNFα levels, β‐thalassaemia major showed limited inflammation compared to SCD. The sVCAM1 increase was significantly lower in patients with SCD receiving exchange compared to simple transfusions. The present results support the involvement of free haem/iron species in the pathogenesis of vascular dysfunction and sterile inflammation in haemolytic diseases, irrespective of the underlying haemolytic mechanism, and highlight the potential therapeutic benefit of iron/haem scavenging therapies in these conditions.

Immunoglobulin G in Platelet-Derived Wound Healing Factors

We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A decreased perfusion of the skin, often associated with conditions such as thalassemia, sickle cell disease, diabetes mellitus, and chronic vascular disease, is the most common etiology of cutaneous ulcers and chronic wounds. We had previously shown that a PDWHF topically applied to a chronic nonhealing ulcer of a β-thalassemia homozygote stimulated and accelerated closure of the wound. The PDWHF was prepared from a pooled platelet concentrate of a matching blood group, consisting of a combination of platelet α-granule-derived factors. Processing of the apheresis-pooled platelets yielded various amounts of proteins (3.36 g/mL ± 0.25 (SD) (N = 10)) by the better lysis buffer method. Immunoglobulin G was found to be the most abundant α-granule-secreted protein. Equally broad quantities of the IgG (10.76 ± 12.66% (SD) (N = 10)) and IgG/albumin ratios (0.6 ± 0.4 (SD) (N = 10)) were quantified. We have developed a method using a reformulated lysis buffer followed by size exclusion chromatography and affinity chromatography to extract, identify, quantify, and purify IgG from activated platelets. IgG purification was confirmed by Western blot and flow cytometry. It was thought unlikely that the platelet IgG could be accounted for by adsorption of plasma protein, though the variable quantities could account for diversity in wound healing rates. The IgG could protect the wound even from subclinical infections and functionally advance healing. It may be useful in the management of skin ulcers in the early phase of wound healing.

Leg ulcers in sickle cell disease patients

Leg ulcers are the most common cutaneous complication of sickle cell disease. These lesions occur mainly in homozygous forms, are slow to heal and often relapse, causing negative physical, emotional, and economic impacts. In this paper, we discuss the clinical presentation, diagnosis, and pathophysiology of sickle cell leg ulcers and their implications for treatment.

Thermographic Characterization of Cutaneous Ulcers of Different Etiologies

The characterization of the temperature of skin ulcers may provide preliminary diagnostic evidence. The aim of this study was to characterize cutaneous ulcers of different etiologies by infrared thermography. 122 cutaneous ulcers of 87 patients (age 60.1 ± 15.7 years) were evaluated, allocated into five groups: venous ulcers (VU) n = 26, arterial ulcers (AU) n = 20, mixed ulcers (MU) n = 25, pressure ulcers (PU) n = 29, and neuropathic ulcers (NU) n = 22. The cutaneous temperature was recorded by infrared thermography (FLIR-450™); we also evaluated the ulcer area, the ankle brachial index (ABI), the range of motion (ROM) of the ankle, and pain. For the different variables, the statistical analysis was performed using the Kruskal Wallis test, ANOVA, the chi-squared test, and the Spearman test (SPSS™ software version 20, p < 0.05). A significant difference was found between the temperatures of PU and NU. The ABI was significantly lower in the MU and AU groups, and pain was also higher in these groups. The ROM was decreased in all groups, and the MU and VU groups had the lowest ROM. There was no correlation between temperature and the clinical findings (ABI, ROM, and pain). There was a moderate correlation in the analysis between the temperature and the area of the ulcer in the PU group, as larger ulcers had lower temperatures. It is possible to characterize cutaneous ulcers by infrared thermography, and there are temperature differences among ulcers with different etiologies.

Fusarium-Induced Cellulitis in an Immunocompetent Patient With Sickle Cell Disease: A Case Report

Fungal infections due to Fusarium species are mostly present in immunocompromised and patients with poorly controlled diabetes mellitus. We report a case of lower extremity skin infection caused by Fusarium species in a 61-year-old woman diagnosed with sickle cell disease. Single skin ulceration caused by Fusarium species can result from fungal inoculation into damaged tissue, so any condition that damages the skin can be considered as a risk factor for inoculation. Long-standing sickle cell disease may develop vaso-occlusion in the skin that can produce lower extremity ulcers and myofascial syndromes. The mechanism is not completely characterized, but compromised blood flow, endothelial dysfunction, thrombosis, inflammation, and delayed healing are thought to contribute to locally compromised tissue that may eventually lead to opportunistic infection such as in our case. Other factors contribute to the pathophysiology of lower extremity ulcers such as diabetes mellitus, with the resulting peripheral vascular ischemia causing poor circulation to the lower extremity, and peripheral neuropathy, which can make patients with diabetes unaware of minor trauma leading to the development of skin infections.

Sickle cell disease clinical phenotypes in Nigeria: A preliminary analysis of the Sickle Pan Africa Research Consortium Nigeria database

BACKGROUND/OBJECTIVE

Sickle cell disease (SCD) is a monogenic disease with multiple phenotypic expressions. Previous studies describing SCD clinical phenotypes in Nigeria were localized, with limited data, hence the need to understand how SCD varies across Nigeria.

METHOD

The Sickle Pan African Research Consortium (SPARCO) with a hub in Tanzania and collaborative sites in Tanzania, Ghana and Nigeria, is establishing a single patient-consented electronic database with a target of 13,000 SCD patients. In collaboration with the Sickle Cell Support Society of Nigeria, 20 hospitals, with paediatric and adult SCD clinics, are participating in patient recruitment. Demographic and clinical information, collected with uniform case report forms, were entered into Excel spreadsheets and uploaded into Research Electronic Data Capture software by trained data clerks and frequency tables generated.

RESULT

Data were available on 3622 patients enrolled in the database, comprising 1889 (52.9%) females and 1434 (39.6%) children ≤15 years. The frequencies of Hb SS, Hb SC and Hb Sβ thalassemia in this data set were 97.5%, 2.5% and 0% respectively. Sixty percent, 23.8%, 5.9%, 4.8% and 2.5% have had bone pain crisis, dactylitis, acute chest syndrome, priapism and stroke respectively. The most frequent chronic complications were: leg ulcers (6.5%), avascular necrosis of bone (6.0%), renal (6.3%) and pulmonary hypertension (1.1%). Only 13.2% had been hospitalized while 67.5% had received blood transfusion.

CONCLUSION

These data on the spectrum of clinical phenotypes of SCD are useful for planning, improving the management of SCD across Nigeria and provide a foundation for genomic research on SCD.

A study of the geographic distribution and associated risk factors of leg ulcers within an international cohort of sickle cell disease patients: the CASiRe group analysis

Vasculopathy is a hallmark of sickle cell disease ultimately resulting in chronic end organ damage. Leg ulcer is one of its sequelae, occurring in ~ 5-10% of adult sickle cell patients. The majority of leg ulcer publications to date have emanated from single center cohort studies. As such, there are limited studies on the geographic distribution of leg ulcers and associated risk factors worldwide. The Consortium for the Advancement of Sickle Cell Research (CASiRe) was formed to improve the understanding of the different phenotypes of sickle cell disease patients living in different geographic locations around the world (USA, UK, Italy, Ghana). This cross-sectional cohort sub-study of 659 sickle cell patients aimed to determine the geographic distribution and risk factors associated with leg ulcers. The prevalence of leg ulcers was 10.3% and was associated with older age, SS genotype, male gender, and Ghanaian origin. In fact, the highest prevalence (18.6%) was observed in Ghana. Albuminuria, proteinuria, increased markers of hemolysis (lower hemoglobin, higher total bilirubin), lower oxygen saturation, and lower body mass index were also associated with leg ulceration. Overall, our study identified a predominance of leg ulcers within male hemoglobin SS patients living in sub-Saharan Africa with renal dysfunction and increased hemolysis.

The effect of natural matrix biopolymer membrane on hard-to-heal venous leg ulcers: a pilot randomised clinical trial

OBJECTIVE

The aim of this study was to evaluate the therapeutic effects of natural matrix biopolymer membrane (NMBM) in the treatment of venous leg ulcers (VLUs).

METHOD

Patients exhibiting one or more VLU were assigned to a test group receiving NMBM or to a control group receiving conventional treatment. Patients exhibiting venous insufficiency-related ulcers within 0.1-170cm² were included. Efficacy was assessed based on ulcer size and visual analogue scale (VAS) pain scores at baseline and at weeks one, two and four. Ulcer size and pain were compared between groups using a two-way ANOVA.

RESULTS

In this study, 25 patients with 32 VLUs (NMBM group: 14 patients with 17 ulcers; control group: 11 patients with 15 ulcers) were included in the final analysis. At four weeks after baseline measurements, the mean percentage change in VLU area of patients in the NMBM group was 61.6% (95% CI: 40.3-82.9) compared with 84.1% (95% CI: 56.5-111.7) for control group patients. Additionally, the mean percentage change in VLU volume of NMBM group patients was 51.2% (95% CI: 31.8-70.6) compared with 84.0% (95% CI: 57.0-121.0) for control group patients. The NMBM group patients exhibited a mean decrease of 0.38 (95% CI: -0.85-1.61) in VAS pain score over four weeks, compared with a mean decrease of 0.13 (95% CI: -1.32-1.58) for control group patients. No significant differences in VLU area (p=0.210), volume (p=0.122) or VAS pain score (p=0.460) were shown between groups.

CONCLUSION

NMBM was found to be as effective and safe as the control group treatments. This pilot study suggests NMBM can be used safely to promote ulcer healing.

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.

High levels of proinflammatory cytokines IL-6 and IL-8 are associated with a poor clinical outcome in sickle cell anemia

Sickle cell anemia (SCA) pathophysiology is characterized by the activation of sickle red blood cells, reticulocytes, leukocytes, platelets, and endothelial cells, and with the expression of several inflammatory molecules. Therefore, it is conceivable that variations in levels of proinflammatory cytokines may act as a signaling of differential clinical course in SCA. Here, we evaluated the clinical impact of proinflammatory cytokines interleukin 1-β (IL-1β), interleukin 6 (IL-6), and interleukin 8 (IL-8) in 79 patients with SCA, followed in a single reference center from northeastern Brazil. The main clinical/laboratory data were obtained from patient interview and medical records. The proinflammatory markers IL-1β, IL-6, and IL-8 were evaluated by using commercially available enzyme-linked immunosorbent assay kits. According to levels of the proinflammatory markers, we observed that patients who had a higher frequency of VOC per year (P = 0.0236), acute chest syndrome (P = 0.01), leg ulcers (P = 0.0001), osteonecrosis (P = 0.0006), stroke (P = 0.0486), and priapism (P = 0.0347) had higher IL-6 levels compared with patients without these clinical complications. Furthermore, increased levels of IL-8 were found in patients who presented leg ulcers (P = 0.0184). No significant difference was found for IL-1β levels (P > 0.05). In summary, the present study emphasizes the role of inflammation in SCA pathophysiology, reveals an association of IL-8 levels and leg ulcer occurrence, and indicates that IL-6 levels can be used as a useful predictor for poor outcomes in SCA.

Neutrophil dysregulation is pathogenic in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are characterized by muscle inflammation and weakness, myositis-specific autoantibodies (MSAs), and extramuscular organ damage. The role of neutrophil dysregulation and neutrophil extracellular traps (NETs) in IIM is unclear. We assessed whether pathogenic neutrophil subsets (low-density granulocytes [LDGs]) and NETs were elevated in IIM, associated with clinical presentation and MSAs, and their effect on skeletal myoblasts and myotubes. Circulating NETs and LDGs were quantified and correlated with clinical measures. Specific MSAs were tested for their ability to induce NETs. NETs and neutrophil gene expression were measured in IIM biopsies. Whether NETs damage skeletal myoblasts and myotubes was tested. Circulating LDGs and NETs were increased in IIM. IIM LDGs had an enhanced ability to form NETs. LDGs and NETs correlated with IIM disease activity and muscle damage. The serum MSA anti-MDA5 correlated with circulating and tissue NETs and directly enhanced NET formation. An enhanced neutrophil gene signature was present in IIM muscle and associated with muscle injury and tissue IFN gene signatures. IIM NETs decreased the viability of myotubes in a citrullinated histone-dependent manner. Dysregulated neutrophil pathways may play pathogenic roles in IIM through their ability to directly injure muscle cells and other affected tissues.

Angiogenesis-Related Genes in Endothelial Progenitor Cells May Be Involved in Sickle Cell Stroke

Background The clinical aspects of sickle cell anemia (SCA) are heterogeneous, and different patients may present significantly different clinical evolutions. Almost all organs can be affected, particularly the central nervous system. Transient ischemic events, infarcts, and cerebral hemorrhage can be observed and affect ≈25% of the patients with SCA. Differences in the expression of molecules produced by endothelial cells may be associated with the clinical heterogeneity of patients affected by vascular diseases. In this study, we investigated the differential expression of genes involved in endothelial cell biology in SCA patients with and without stroke. Methods and Results Endothelial progenitor cells from 4 SCA patients with stroke and 6 SCA patients without stroke were evaluated through the polymerase chain reaction array technique. The analysis of gene expression profiling identified 29 differentially expressed genes. Eleven of these genes were upregulated, and most were associated with angiogenesis (55%), inflammatory response (18%), and coagulation (18%) pathways. Downregulated expression was observed in 18 genes, with the majority associated with angiogenesis (28%), apoptosis (28%), and cell adhesion (22%) pathways. Remarkable overexpression of the MMP1 (matrix metalloproteinase 1) gene in the endothelial progenitor cells of all SCA patients with stroke (fold change: 204.64; P=0.0004) was observed. Conclusions Our results strongly suggest that angiogenesis is an important process in sickle cell stroke, and differences in the gene expression profile of endothelial cell biology, especially MMP1, may be related to stroke in SCA patients.

Methylene tetrahydrofolate reductase gene mutation in sickle cell anaemia patients in Lagos, Nigeria

Introduction

The significant causes of mortality among individuals with sickle cell anaemia (SCA) such as acute chest syndrome and cerebrovascular disease are related to vascular occlusion. Polymorphisms of the methylene tetrahydrofolate reductase (MTHFR) gene in persons with sickle cell anaemia have been suggested as a potential risk for vaso-occlusive events, with the C677T and A1298C polymorphisms being the commonest. This study therefore aimed to establish the pattern of MTHFR C677T and A1298C gene mutations among adults with HbSS phenotype attending the Haematology Clinic in Lagos State University Teaching Hospital Lagos, Nigeria.

Methods

A cross-sectional study was done among SCA patients attending the Haematology Clinic of the Lagos State University Teaching Hospital (LASUTH), using age and sex matched HbAA controls. DNA extraction and gene analysis were done. The selective amplification of a particular segment of the DNA by polymerase chain reaction (PCR) was done and subsequent digestion of the amplified MTHFR gene into its various fragments.

Results

The overall prevalence of the C677T mutation among participants was 19.3% (37 of 192), while the prevalence of A1298C was 15% (29 of 192).

Conclusion

The prevalence of MTHFR C677T was higher than A1298C mutations among sickle cell anaemia subjects.

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.

Retinal oximetry and fractal analysis of capillary maps in sickle cell disease patients and matched healthy volunteers

PURPOSE

Fractal analysis can be used to quantitatively analyze the retinal microvasculature and might be a suitable method to quantify retinal capillary changes in sickle cell disease (SCD) patients. Retinal oximetry measurements might function as a proxy for the pathophysiology of cerebrovascular diseases. Moreover, hypoxia has an important role in the pathophysiology of diabetic and other retinopathies. However, little is known about the oximetry around the macula in SCD patients. With this study, we explored the feasibility to perform these quantified measurements in SCD patients.

METHODS

Retinal microvascular and oximetry measurements were performed in eight SCD patients and eight healthy matched controls. Oximetry pictures and non-invasive capillary perfusion maps (nCPM) were obtained by the retinal function imager. Measurements were conducted twice on two different study days. Measured variables included monofractal dimension (Dbox), relative saturation, deoxygenated hemoglobin (deoxyHb), and oxygenated hemoglobin (oxyHb) concentration.

RESULTS

No statistically significant differences in vessel density were found in the different annular zones (large vessels, p = 0.66; small vessels, p = 0.66) and anatomical quadrants (large vessels, p = 0.74; small vessels, p = 0.72). Furthermore, no significant between-group differences were found in the other different anatomical quadrants and annular zones around the fovea for relative saturation levels and deoxygenated Hb. However, the oxyHb levels were significantly lower in SCD patients, compared with those in matched controls in the temporal quadrants (p = 0.04; p = 0.02) and the superior nasal quadrant (p = 0.05).

CONCLUSIONS

Our study demonstrated the feasibility of multispectral imaging to measure retinal changes in oxygenation in both SCD patients and matched volunteers. The results suggest that in SCD patients before any structural microvascular changes in the central retina are present, functional abnormalities can be observed with abnormal oximetry measurements.

Nitric Oxide-Independent Soluble Guanylate Cyclase Activation Improves Vascular Function and Cardiac Remodeling in Sickle Cell Disease

Sickle cell disease (SCD) is associated with intravascular hemolysis and oxidative inhibition of nitric oxide (NO) signaling. BAY 54-6544 is a small-molecule activator of oxidized soluble guanylate cyclase (sGC), which, unlike endogenous NO and the sGC stimulator, BAY 41-8543, preferentially binds and activates heme-free, NO-insensitive sGC to restore enzymatic cGMP production. We tested orally delivered sGC activator, BAY 54-6544 (17 mg/kg/d), sGC stimulator, BAY 41-8543, sildenafil, and placebo for 4-12 weeks in the Berkeley transgenic mouse model of SCD (BERK-SCD) and their hemizygous (Hemi) littermate controls (BERK-Hemi). Right ventricular (RV) maximum systolic pressure (RVmaxSP) was measured using micro right-heart catheterization. RV hypertrophy (RVH) was determined using Fulton's index and RV corrected weight (ratio of RV to tibia). Pulmonary artery vasoreactivity was tested for endothelium-dependent and -independent vessel relaxation. Right-heart catheterization revealed higher RVmaxSP and RVH in BERK-SCD versus BERK-Hemi, which worsened with age. Treatment with the sGC activator more effectively lowered RVmaxSP and RVH, with 90-day treatment delivering superior results, when compared with other treatments and placebo groups. In myography experiments, acetylcholine-induced (endothelium-dependent) and sodium-nitroprusside-induced (endothelium-independent NO donor) relaxation of the pulmonary artery harvested from placebo-treated BERK-SCD was impaired relative to BERK-Hemi but improved after therapy with sGC activator. By contrast, no significant effect for sGC stimulator or sildenafil was observed in BERK-SCD. These findings suggest that sGC is oxidized in the pulmonary arteries of transgenic SCD mice, leading to blunted responses to NO, and that the sGC activator, BAY 54-6544, may represent a novel therapy for SCD-associated pulmonary arterial hypertension and cardiac remodeling.

Intima-media thickness of the common femoral artery as a marker of leg ulceration in sickle cell disease patients

Leg ulceration is a debilitating chronic complication of sickle cell disease (SCD) the pathogenesis of which is yet to be fully elucidated. We hypothesized that SCD patients with histories of previous leg ulcers would have intima hyperplasia of the common femoral artery (CFA). We enrolled 44 SCD patients and 33 age-matched and sex-matched controls with hemoglobin AA. Anthropometric measurements, biochemical parameters, and sonographic intima-media thickness (IMT) of the CFA were determined. The median CFA IMT in SCD limbs with history of leg ulcers (SWLU) was 1.0 mm, whereas it was 0.7 mm in SCD limbs with no history of leg ulcer (SNLU) and 0.60 mm in controls (P < .001). Among the SNLU, 70.3% had CFA IMT <0.9 mm, whereas only 29.7% had CFA IMT ≥0.9 mm. Conversely, only 20.8% of SWLU had CFA IMT <0.9 mm, whereas the remaining 79.2% had CFA IMT ≥0.9 mm. All the controls had CFA IMT <0.9 mm. Binary logistic regression to determine the odds of having leg ulcer among SCD limbs with CFA IMT of ≥0.9 mm yielded an odds ratio of 9, indicating that SCD limbs with CFA IMT ≥0.9 mm had a 9 times greater risk of having leg ulcer compared with those with CFA IMT <0.9 mm. There is a significant increase in the CFA IMT of SCD limbs with ulcer compared with controls and SCD limbs without ulcer, suggesting that arterial vasculopathy plays a major role in the formation of these ulcers.

Iron Chelation with Transdermal Deferoxamine Accelerates Healing of Murine Sickle Cell Ulcers

Objective: Sickle cell ulcers (SCUs) are a devastating comorbidity affecting patients with sickle cell disease (SCD). SCUs form over the medial or lateral malleoli of the lower extremity, are slow to heal, and prone to recidivism. Some SCUs may never heal, leading to chronic pain and foot deformities. There is no specific and effective therapy for SCUs. Systemic deferoxamine (DFO) has been demonstrated to prevent some of the sequelae of SCD by chelating iron. In this study, we tested the ability of DFO delivered via a transdermal delivery system (DFO-TDDS) to accelerate healing in a murine model of SCU. Approach: Excisional wounds were created in a transgenic murine model of SCD expressing >99% human sickle hemoglobin, and healing rates were compared with wounds in wild-type mice. Next, excisional wounds in SCD mice were treated with DFO-TDDS, DFO injection, or left untreated. Wound closure rates, histology, and iron in the healed wounds were analyzed. Results: Wounds in SCD mice healed significantly slower than wild-type mice (***p < 0.001). DFO-TDDS-treated wounds demonstrated significantly accelerated time to closure, reduced size, and improved wound remodeling compared with untreated wounds (***p < 0.001) and DFO injection treatment (*p < 0.05). DFO released from the TDDS into wounds resulted in chelation of excessive dermal-free iron. Innovation: DFO-TDDS is a novel therapeutic that is effective in healing wounds in sickle cell mice. Conclusion: DFO-TDDS significantly accelerates healing of murine SCUs by chelation of excessive free iron and is currently manufactured in an FDA-compliant facility to be translated for treating human SCUs.

Inflammation in sickle cell disease

The primary β-globin gene mutation that causes sickle cell disease (SCD) has significant pathophysiological consequences that result in hemolytic events and the induction of the inflammatory processes that ultimately lead to vaso-occlusion. In addition to their role in the initiation of the acute painful vaso-occlusive episodes that are characteristic of SCD, inflammatory processes are also key components of many of the complications of the disease including autosplenectomy, acute chest syndrome, pulmonary hypertension, leg ulcers, nephropathy and stroke. We, herein, discuss the events that trigger inflammation in the disease, as well as the mechanisms, inflammatory molecules and cells that propagate these inflammatory processes. Given the central role that inflammation plays in SCD pathophysiology, many of the therapeutic approaches currently under pre-clinical and clinical development for the treatment of SCD endeavor to counter aspects or specific molecules of these inflammatory processes and it is possible that, in the future, we will see anti-inflammatory drugs being used either together with, or in place of, hydroxyurea in those SCD patients for whom hematopoietic stem cell transplants and evolving gene therapies are not a viable option.

Critical Reviews: How we treat sickle cell patients with leg ulcers

The past five decades have seen an improvement in the mortality and morbidity of sickle cell disease (SCD) because of prophylaxis against infectious complications, improved and expanded red cell transfusions, implementation of hydroxyurea therapy, and advances in supportive care. Now that the majority of patients in the western hemisphere reaches adulthood, end organ diseases are frequent, which include vasculopathic complications such as chronic leg ulcers. The management of patients with leg ulcers requires the hematologist to lead a team of health care professionals, and investigates the presence of associated, but potentially still occult signs of vasculopathy, such as pulmonary hypertension, renal disease, priapism and retinopathy. These complications may be asynchronous, and long term careful screening is indicated, in order to ensure early diagnosis and intervention. It is crucial to address both the immediate consequences of pain, infection and disability, and long term effects on quality of life, employment and stigma associated with chronic ulceration. Recent insights into their pathophysiology may have practical implications. We propose a holistic approach to the management of patients' physical and emotional problems and mechanisms of ulcers formation and delayed healing. An overview of topical and systemic therapies for chronic ulcers is given, with the understanding that wound care therapy is best left to the wound specialists, medical and surgical, with whom the hematologist must keep an open line of communication. In the absence of evidence-based guidelines, our opinion is based on both a critical review of the literature and our personal clinical and research experience.

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

Leg ulcers are a major complication of sickle cell disease that occur in 2.5-40% of patients. Leg ulcers are responsible for frequent complications because they are often long-lasting and are highly resistant to therapy. Although their occurrence is associated with hyperhemolysis, the mechanisms underlying sickle cell ulcers remain poorly understood. In this study, we show that skin wound healing is severely altered in old SAD sickle cell mice but is normal in young animals, consistent with reports in humans. Alterations of wound healing were associated with impaired blood and lymphatic angiogenesis in the wound beds and poor endothelial progenitor cell mobilization from the bone marrow. CXCL12 secretion by keratinocytes and inflammatory cells was low in the wounds of SAD mice. Local therapy with endothelial progenitor cells or recombinant CXCL12 injections restored wound angiogenesis and rescued the healing defect together with mobilization of circulating endothelial progenitor cells. To our knowledge, this is a previously unreported study of the cellular and molecular mechanisms of sickle cell ulcers in a murine model that provides promising therapeutic perspectives for clinical trials.

A treatment algorithm to identify therapeutic approaches for leg ulcers in patients with sickle cell disease

Sickle cell leg ulcers (SCLUs) are a common complication of sickle cell disease (SCD). Patients who develop ulcers appear to have a more severe haemolysis-associated vasculopathy than individuals who do not develop them, and manifest other complications such as priapism and pulmonary hypertension. SCLUs are slow to heal and often recur, affecting both the emotional and physical well-being of patients. Here we summarise what is known about the pathophysiology of SCLUs, describe available treatment options and propose a treatment algorithm.

Management of the Dialysis Patient with Sickle Cell Disease

While patients with sickle cell disease currently constitute a very small minority of the US dialysis population (0.1%), there is anticipated growth of this group as the life expectancy of those with sickle cell disease (SCD) increases. SCD patients suffer a high burden of morbidity, which is enhanced by the presence of end-stage renal disease (ESRD). In this review, we discuss the pathophysiology of SCD and the basic tenets of its management with focus on the dialysis patient with SCD. Anemia in dialysis patients with SCD is a unique challenge. The hemoglobin target in SCD dialysis patients with ESRD should not exceed 10 g/dl. SCD patients, and particularly those on dialysis, are likely to be poorly responsive to erythropoietin-stimulating agent (ESA) therapy and might be at increased risk for vaso-occlusive crisis (VOC) with ESA. Iron chelation and hydroyxurea therapy require special considerations and modifications in dialysis patients with SCD. There are theoretical advantages to both hemodialysis (HD) and peritoneal dialysis (PD) in SCD patients. With HD, there is a secure vascular access available for both standard and exchange blood transfusion in patients who need them. With PD, the absence of an acute rise in hematocrit with ultrafiltration (UF) might offer lower risk of VOC. During VOC, reduction in UF goals should be considered but administration of intravenous fluids should be reserved only for clear cases of volume depletion. Finally, renal transplantation appears to confer a survival advantage to dialysis in SCD patients and should be pursued when possible.

Topical fentanyl stimulates healing of ischemic wounds in diabetic rats

BACKGROUND

Topically applied opioids promote angiogenesis and healing of ischemic wounds in rats. We examined if topical fentanyl stimulates wound healing in diabetic rats by stimulating growth-promoting signaling, angiogenesis, lymphangiogenesis and nerve regeneration.

METHODS

We used Zucker diabetic fatty rats that develop obesity and diabetes on a high fat diet due to a mutation in the Leptin receptor. Fentanyl blended with hydrocream was applied topically on ischemic wounds twice daily, and wound closure was analyzed regularly. Wound histology was analyzed by hematoxylin and eosin staining. Angiogenesis, lymphangiogenesis, nerve fibers and phospho-platelet derived growth factor receptor-β (PDGFR-β) were visualized by CD31-, lymphatic vessel endothelium-1, protein gene product 9.5- and anti-phospho PDGFR-β-immunoreactivity, respectively. Nitric oxide synthase (NOS) and PDGFR-β signaling were analyzed using Western immunoblotting.

RESULTS

Fentanyl significantly promoted wound closure as compared to phosphate-buffered saline (PBS). Histology scores were significantly higher in fentanyl-treated wounds, indicative of increased granulation tissue formation, reduced edema and inflammation, and increased matrix deposition. Fentanyl treatment resulted in increased wound angiogenesis, lymphatic vasculature, nerve fibers, nitric oxide, NOS and PDGFR-β signaling as compared to PBS. Phospho-PDGFR-β co-localized with CD31 co-staining for vasculature.

CONCLUSIONS

Topically applied fentanyl promotes closure of ischemic wounds in diabetic rats. Increased angiogenesis, lymphangiogenesis, peripheral nerve regeneration, NO and PDGFR-β signaling are associated with fentanyl-induced tissue remodeling and wound healing.

Morphine for the treatment of pain in sickle cell disease

Pain is a hallmark of sickle cell disease (SCD) and its treatment remains challenging. Opioids are the major family of analgesics that are commonly used for treating severe pain. However, these are not always effective and are associated with the liabilities of their own. The pharmacology and multiorgan side effects of opioids are rapidly emerging areas of investigation, but there remains a scarcity of clinical studies. Due to opioid-induced endothelial-, mast cell-, renal mesangial-, and epithelial-cell-specific effects and proinflammatory as well as growth influencing signaling, it is likely that when used for analgesia, opioids may have organ specific pathological effects. Experimental and clinical studies, even though extremely few, suggest that opioids may exacerbate existent organ damage and also stimulate pathologies of their own. Because of the recurrent and/or chronic use of large doses of opioids in SCD, it is critical to evaluate the role and contribution of opioids in many complications of SCD. The aim of this review is to initiate inquiry to develop strategies that may prevent the inadvertent effect of opioids on organ function in SCD, should it occur, without compromising analgesia.

High red blood cell nitric oxide synthase activation is not associated with improved vascular function and red blood cell deformability in sickle cell anaemia

Human red blood cells (RBC) express an active and functional endothelial-like nitric oxide (NO) synthase (RBC-NOS). We report studies on RBC-NOS activity in sickle cell anaemia (SCA), a genetic disease characterized by decreased RBC deformability and vascular dysfunction. Total RBC-NOS content was not significantly different in SCA patients compared to healthy controls; however, using phosphorylated RBC-NOS-Ser(1177) as a marker, RBC-NOS activation was higher in SCA patients as a consequence of the greater activation of Akt (phosphorylated Akt-Ser(473) ). The higher RBC-NOS activation in SCA led to higher levels of S-nitrosylated α- and β-spectrins, and greater RBC nitrite and nitrotyrosine levels compared to healthy controls. Plasma nitrite content was not different between the two groups. Laser Doppler flowmetric experiments demonstrated blunted microcirculatory NO-dependent response under hyperthermia in SCA patients. RBC deformability, measured by ektacytometry, was reduced in SCA in contrast to healthy individuals, and pre-shearing RBC in vitro did not improve deformability despite an increase of RBC-NOS activation. RBC-NOS activation is high in freshly drawn blood from SCA patients, resulting in high amounts of NO produced by RBC. However, this does not result in improved RBC deformability and vascular function: higher RBC-NO is not sufficient to counterbalance the enhanced oxidative stress in SCA.

Autologous Platelet Gel

Leg ulcers represent a particularly disabling complication in patients with sickle cell disease (SCD). Platelet gel (PG) is a novel therapeutic strategy used for accelerating wound healing of a wide range of tissues through the continuous release of platelet growth factors. Here, we describe the use of PG preparation according to Anitua’s PRGF (preparations rich in growth factors) protocol for treating chronic nonhealing ulcers in patients with SCD. A positive response occurred in 3 patients with an area reduction of 85.7% to 100%, which occurred within 7 to 10 weeks, and a 35.2% and 20.5% of area reduction in 2 other patients, who however, had large ulcers. After calcium chloride addition, the platelet-rich plasmas demonstrated enhanced platelet-derived growth factors–BB ( P < .001), transforming growth factor-β1 ( P = .015), vascular endothelial growth factors ( P = .03), and hepatocyte growth factors (nonsignificant) secretion. Furthermore, calcium chloride addition induced a significant decrease in platelet number ( P = .0134) and there was no leukocyte detection in the PG product. These results demonstrate that PG treatment might impact the healing of leg ulcers in sickle cell disease, especially in patients with small ulcers.

Decreased hematocrit-to-viscosity ratio and increased lactate dehydrogenase level in patients with sickle cell anemia and recurrent leg ulcers

Leg ulcer is a disabling complication in patients with sickle cell anemia (SCA) but the exact pathophysiological mechanisms are unknown. The aim of this study was to identify the hematological and hemorheological alterations associated with recurrent leg ulcers. Sixty-two SCA patients who never experienced leg ulcers (ULC-) and 13 SCA patients with a positive history of recurrent leg ulcers (ULC+) - but with no leg ulcers at the time of the study – were recruited. All patients were in steady state condition. Blood was sampled to perform hematological, biochemical (hemolytic markers) and hemorheological analyses (blood viscosity, red blood cell deformability and aggregation properties). The hematocrit-to-viscosity ratio (HVR), which reflects the red blood cell oxygen transport efficiency, was calculated for each subject. Patients from the ULC+ group were older than patients from the ULC- group. Anemia (red blood cell count, hematocrit and hemoglobin levels) was more pronounced in the ULC+ group. Lactate dehydrogenase level was higher in the ULC+ group than in the ULC- group. Neither blood viscosity, nor RBC aggregation properties differed between the two groups. HVR was lower and RBC deformability tended to be reduced in the ULC+ group. Our study confirmed increased hemolytic rate and anemia in SCA patients with leg ulcers recurrence. Furthermore, our data suggest that although systemic blood viscosity is not a major factor involved in the pathophysiology of this complication, decreased red blood cell oxygen transport efficiency (i.e., low hematocrit/viscosity ratio) may play a role.