Automated red blood cell exchange with a post-procedure haematocrit targeted at 34% in the chronic management of sickle cell disease.

Optimal targets for red blood cell exchange (RCE) are not well defined in the chronic management of sickle cell disease. We analysed transfusion requirements and iron-related outcomes in 101 patients on chronic RCE with a post-procedure haematocrit (Ht) targeted at 34%, which is higher than typically used. A majority were of HbSS/HbSß0 genotype (n = 72) and enrolled for neurological complications (n = 53). Fifty patients had a positive Ht balance with RCE (>2% mean increase from pre-procedure level), while 43 patients maintained a neutral balance. The first group required fewer red blood cell units/year (65 vs. 80, p < 0.001), but a significant proportion were iron overloaded based on R2* with liver MRI (32% vs. none performed) and prescription of iron chelation (52% vs. 0%, p < 0.001, after a median of 19 months). The second group was more likely to receive iron supplementation (6% vs. 56%, p < 0.001). Chronic automated RCE with a post-procedure Ht targeted at 34% is not iron-neutral, and personalized Ht goals may be more appropriate in certain settings. This higher target should be compared with a lower Ht strategy in individuals with similar baseline red cell volumes to assess iron homeostasis and blood product requirements.

Emerging drugs for the treatment of sickle cell disease: a review of phase II/III trials.

INTRODUCTION: The substitution of glutamic acid by valine on the ß-globin chain produces the hemoglobin S variant responsible for sickle cell disease (SCD), a disorder that affects millions of people worldwide and leads to acute and cumulative organ damage. Even though life expectancy has significantly improved where the best medical care is available, there are still few therapeutic options for SCD and those are limited by their availability, cost, and individual toxicities. AREAS COVERED: This review summarizes the clinical data on current treatments for SCD and emerging therapies studied in the acute setting as well as potential disease-modifying agents, with an emphasis on the FDA-approved agents. EXPERT OPINION: Hydroxyurea has been a gold standard for two decades, showing benefits in acute complications and overall survival in sickle cell anemia, although data is lacking for certain genotypes such as hemoglobin SC. As progress is made in our understanding of the pathophysiological networks characterizing SCD, numerous pathways appear to be targetable, with L-glutamine, crizanlizumab and voxelotor now approved by the FDA. Pursuing a multi-agent approach could alter the disease course in a more effective fashion and provide an alternative option to curative therapies, but longer clinical studies are needed.

Positive impacts of universal newborn screening on the outcome of children with sickle cell disease in the province of Quebec: A retrospective cohort study.

A universal newborn screening program for sickle cell disease (uNS-SCD) was implemented in the province of Québec (Qc) in November 2013, close in time to the recommendation of early initiation of hydroxyurea (HU) therapy for children. This retrospective cohort study evaluated the impact of such a program on children first seen between January 2000 and December 2019. Cohorts pre-SCD-uNS in Qc (pre-QcNS) (n = 253) and post-QcNS (n = 157) for patients seen prior to or after Nov 2013 were compared. Kaplan-Meier curves, Poisson regression, and logistic regressions were used for statistical analysis, using Software R version 4.2.1. Median age at first visit decreased significantly from 14.4 [interquartile range: 2.4-72.0] to 1.2 months [1.2-57.6] (p < 0.001). The percentage of children born in Qc undiagnosed at birth and referred after a first SCD-related complication dropped from 42.6% to 0.0% (p < 0.0001). The median age of HU introduction for patients with SS/Sß°-thalassemia decreased from 56.4 [31.2-96.0] to 9.0 months post-QcNS [8.0-12.1] (p < 0.001). Event-free survival improved significantly for any type of hospitalization as well as for vaso-occlusive crisis (VOC) (140-257 days (p < 0.001) and 1320 vs. 573 days (p < 0.002), respectively), resulting in a reduction from 2 [interquartile range: 1.0-3.0] to 1.0 hospitalizations/patient-year [0.6-1.4] (p < 0.001). Children with SS/Sß°-thalassemia referred post-QcNS also had fewer emergency department visits for VOC (RR: 0.69, 95% confidence interval: 0.54-0.88). The Universal NS program allows early detection and referral of children with SCD to comprehensive care centers. Earlier access ensures that children benefit from essential preventive interventions, reducing disease burden. This cohort study highlights that uNS-SCD is an essential public health measure.

THromboprophylaxis In Sickle Cell Disease with central venous catheters (THIS): an internal pilot randomised controlled trial protocol.

INTRODUCTION: Individuals with sickle cell disease (SCD) and central venous catheters (CVC) are at high risk for venous thromboembolism (VTE). Minimal data exist regarding the use of anticoagulation as thromboprophylaxis of VTE in this demographic, and as a result, clinical equipoise exists. Prophylactic dose rivaroxaban, a direct oral anticoagulant, is efficacious and safe as thromboprophylaxis in other demographics, and may be an optimal agent in SCD with CVC. Prior to conducting a full clinical trial to assess rivaroxaban as thromboprophylaxis in SCD with CVC, a pilot study is needed to gauge its feasibility. METHODS AND ANALYSIS: THromboprophylaxis In Sickle Cell Disease pilot trial is an investigator-initiated, multicentre, double-blinded, randomised controlled trial (RCT) assessing if it is feasible and safe to conduct an adequately powered RCT comparing rivaroxaban to matching placebo as thromboprophylaxis in those with SCD and CVC. Fifty adult patients with SCD and CVC will be randomised to receive either rivaroxaban 10 mg daily or matching placebo for the duration of the CVC in situ for up to 1 year. After randomisation, follow-up visits will occur every 3 months. The primary outcomes pertain to the feasibility of a full trial and include numbers of eligible and recruited participants. Exploratory outcomes include overall incidence of VTE and bleeding complications, as well as quality of life. If the full trial is feasible, blinding will be maintained and patients in the pilot study will be included in the full trial. ETHICS AND DISSEMINATION: The trial was initially approved by the University Health Network Research Ethics Board (REB) in Toronto, Canada. All sites will obtain approval from their respective REB prior to commencement of study activities. Study results will be disseminated through presentations at medical conferences and peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT05033314.

Near-Infrared Spectroscopy Demonstrates the Benefit of Erythracytapheresis in Sickle Cell Disease Adult Patients with Cerebral Vasculopathy.

BACKGROUND: Cerebral vasculopathy can induce chronic cerebral hypoperfusion leading to stroke in patients with sickle cell disease (SCD) and is treated by blood exchange transfusion (BET). However, no prospective clinical study has demonstrated the benefit of BET in adults with SCD and cerebral vasculopathy. Near Infrared Spectroscopy (NIRS) is a recent non-invasive method complementary to Magnetic Resonance Imaging (MRI). We evaluated cerebral perfusion using NIRS during erythracytapheresis in patients with SCD with and without steno-occlusive arterial disease. METHODS: We conducted a monocentric, prospective study in 16 adults with SCD undergoing erythracytapheresis in 2014. Among them, 10 had cerebral steno-occlusive arterial disease. NIRS measured the relative amounts of oxyhemoglobin (OxyHb), deoxyhemoglobin (DeoxyHb) and total hemoglobin (Total Hb) in brain tissue and in muscle. RESULTS: In cerebral hemispheres associated with steno-occlusive arterial disease, we observed a significant increase of OxyHb and Total Hb during BET, without modification of DeoxyHb. CONCLUSION: Using NIRS during BET showed that BET improves cerebral perfusion in adult patients with SCD with cerebral vasculopathy.

Early Strokes Are Associated with More Global Cognitive Deficits in Adults with Sickle Cell Disease.

This study sought to link neurocognitive profiles in sickle cell disease (SCD) patients with clinical characteristics. We conducted a prospective cohort study of adults with SCD who underwent comprehensive neuropsychological assessment at the UMGGR clinic at Henri Mondor Hospital, Créteil (France). A cluster analysis was performed based on neuropsychological testing scores. The association between clusters and clinical profiles was assessed. Between 2017 and 2021, 79 patients with a mean age of 36 [range 19-65] years were included. On principal component analysis, a 5-factor model presented the best fit (Bartlett's sphericity test [χ2 (171) = 1345; p < 0.001]), explaining 72% of the variance. The factors represent distinct cognitive domains and anatomical regions. On hierarchical classification, three clusters emerged. Cluster 1 (n = 24) presented deficits in all five factors compared to Cluster 3 (n = 33). Cluster 2 (n = 22) had deficits in all factors, but to a lesser extent than Cluster 1. MoCA scores mirrored the severity of these cognitive deficits. Age, genotype and stroke prevalence did not differ significantly between clusters. However, the time of first stroke occurrence differed significantly between Cluster 1 and 2-3: 78% of strokes occurred during childhood, whereas 80% and 83% occurred during adulthood in Clusters 2 and 3, respectively. Educational attainment was also reduced in Cluster 1. SCD patients with childhood stroke seem to be at increased risk of a global cognitive deficit profile. In addition to existing methods of primary and secondary stroke prevention, early neurorehabilitation should be prioritized in order to reduce the long-term cognitive morbidity of SCD.

COVID-19 outcomes in patients with sickle cell disease and sickle cell trait compared with individuals without sickle cell disease or trait: a systematic review and meta-analysis.

Background: Clinical manifestations and severity of SARS-CoV-2 infection in individuals with sickle cell disease (SCD) and sickle cell trait (SCT) are not well understood yet. Methods: We performed a systematic review and meta-analysis to assess COVID-19 outcomes in individuals with SCD or SCT compared to individuals without sickle cell disease or trait. An electronic search on PubMed, Embase, and Cochrane Library was performed on August 3, 2023. Two authors (IFM and ISP) independently screened (IFM and ISP) and extracted data (IFM and ILC) from included studies. Main exclusion criterion was the absence of the non-SCD/SCT group. Exposure effects for binary endpoints were compared using pooled odds ratio (OR) with 95% confidence intervals (CI). I2 statistics was used to assess the heterogeneity and DerSimonian and Laird random-effects models were applied for all analyses to minimize the impact of differences in methods and outcomes definitions between studies. The overall quality of evidence was assessed using the GRADE system. Review Manager 5.4 and R software (v4.2.2) were used for statistical analyses. Registered with PROSPERO, CRD42022366015. Findings: Overall, 22 studies were included, with a total of 1892 individuals with SCD, 8677 individuals with SCT, and 1,653,369 individuals without SCD/SCT. No difference in all-cause mortality was seen between SCD/SCT and non-SCD/SCT (OR 1.18; 95% CI 0.78-1.77; p = 0.429; I2 = 82%). When considering only studies adjusted for confounders (8 studies), patients with SCD/SCT were shown to be at increased risk of death (OR 1.86; 95% CI 1.30-2.66; p = 0.0007; I2 = 34%). No significant difference was seen between individuals with SCD and SCT (p = 0.863). The adjusted for confounders analysis for hospitalisation revealed higher rates for the SCD (OR 5.44; 95% CI 1.55-19.13; p = 0.008; I2 = 97%) and the SCT groups (OR 1.31; 95% CI 1.10-1.55; p = 0.002; I2 = 0) compared to the non-SCD/SCT population. Moreover, it was significantly higher for the SCD group (test for subgroup difference; p = 0.028). Interpretation: Our findings suggest that patients with SCD or SCT may present with a higher mortality and hospitalisation rates due to COVID-19 infection. Funding: None.

Screening for cognitive impairment in adults with sickle cell disease: A systematic review and meta-analysis.

Neurovascular disease such as symptomatic stroke, silent brain infarcts and vascular cognitive impairment are common complications of sickle cell disease (SCD) that can have devastating consequences on quality of life, employment, and social functioning.  Early recognition of neurovascular disease is a prerequisite for the timely optimization of medical care and to connect patients to adaptive resources. While cognitive impairment has been well described in children, currently available data are limited in adults. As a result, guidance on the optimal cognitive screening strategies in adults is scarce. We conducted a systematic review to identify the different screening tools that have been evaluated in SCD. A meta-analysis was performed to estimate the prevalence of suspected cognitive impairment in this population. In this qualitative synthesis, we present 8 studies that evaluated 6 different screening tools. Patient characteristics that impacted on cognitive screening performance included age, education level, and a prior history of stroke. We report a pooled prevalence of 38% [14-62%] of suspected cognitive impairment. We discuss the relative benefits and limitations of the different screening tools to help clinicians select an adapted approach tailored to their specific patients' needs. Further studies are needed to establish and validate cognitive screening strategies in patients with diverse cultural and educational backgrounds.

Prospective Evaluation of Fetal Hemoglobin Expression in Maternal Erythrocytes: An Analysis of a Cohort of 345 Parturients.

It is believed that fetal hemoglobin (HbF) expression in adults is largely genetically regulated. The increased expression of HbF in pregnancy has been reported in a small number of articles. Different mechanisms have been proposed, but the description of HbF expression during pregnancy remains unclear. The objectives of this study were to document HbF expression during peri and postpartum periods, confirm its maternal origin, and assess clinical and biochemical parameters potentially associated with HbF modulation. In this observational prospective study, 345 pregnant women were followed. At baseline, 169 had HbF expression (≥1% of total hemoglobin) and 176 did not have HbF expression. Women were followed at the obstetric clinic during their pregnancy. Clinical and biochemical parameters were measured at each visit. Analyses were made to determine which parameters had a significant correlation to HbF expression. Results show that HbF expression of ≥1% during peri and postpartum periods in pregnant women without influencing comorbidities is at its highest peak during the first trimester. In all women, it was proven that HbF was of maternal origin. A significant positive correlation between HbF expression, ßeta-human chorionic gonadotropin (ß-HCG), and glycosylated hemoglobin (HbA1c) was present. A significant negative association between HbF expression and total hemoglobin was found. HbF expression induction during pregnancy is probably associated with an increase in ß-HCG and HbA1C, and a decrease in total hemoglobin, which could temporarily reactivate the fetal erythropoietic system.

Numb Chin Syndrome in Sickle Cell Disease: A Systematic Review and Recommendations for Investigation and Management.

Numb chin syndrome (NCS) is a rare sensory neuropathy resulting from inferior alveolar or mental nerve injury. It manifests as hypoesthesia, paraesthesia, or, rarely, as pain in the chin and lower lip. Several case reports suggest that sickle cell disease (SCD) could be a cause of NCS. However, information about NCS is scarce in this population. Our objectives were to synthesize all the available literature relevant to NCS in SCD and to propose recommendations for diagnosis and management based on the best available evidence. A systematic review was performed on several databases to identify all relevant publications on NCS in adults and children with SCD. We identified 73 publications; fourteen reports met the inclusion/exclusion criteria. These described 33 unique patients. Most episodes of NCS occurred in the context of typical veno-occlusive crises that involved the mandibular area. Radiological signs of bone infarction were found on some imaging, but not all. Neuropathy management was mostly directed toward the underlying cause. Overall, these observations suggest that vaso-occlusion and bone infarction could be important pathophysiological mechanisms of NCS. However, depending on the individual context, we recommend a careful evaluation to rule out differential causes, including infections, local tumors, metastatic disease, and stroke.

Should Magnetic Resonance Angiography Be Used for Screening of Intracranial Aneurysm in Adults with Sickle Cell Disease?

Magnetic resonance imaging (MRI) is used in patients with sickle cell disease (SCD) to detect silent cerebral infarcts. MR angiography (MRA) can identify arterial stenoses and intracranial aneurysms (ICANs) associated with SCD. In this study, we aimed to estimate the prevalence of ICANs in asymptomatic adult patients with SCD referred from the SCD clinic for routine screening by MRI/MRA using a 3T-MRI scanner. Findings were independently reviewed by two neuroradiologists. Between 2016 and 2020, 245 asymptomatic adults with SCD were stratified according to genotype (SS/S-ß0thalassemia and SC/Sß+). ICANs were found in 27 patients (11%; 0.95 CI: 8-16%). ICANs were more frequent in SS/S-ß0thalassemia patients (20/118 or 17%; 0.95 CI: 11-25%) than in SC/ßb+ patients (7/127 or 6%; 0.95 CI: 2-11%; p = 0.007). Individuals with SCD (particularly SS/S-ß0thalassemia) have a higher prevalence of ICANs than the general population. We believe that MRA should be considered in the current American Society of Hematology guidelines, which already contain a recommendation for MRI at least once in adult SCD patients. However, the clinical significance of preventive treatment of unruptured aneurysms remains controversial.

Sickle cell cerebrovascular reactivity to a CO2 stimulus: Too little, too slow.

Background: Despite increased cerebral blood flow (CBF), cerebral infarcts occur in patients with sickle cell disease (SCD). This suggests increased CBF does not meet metabolic demand possibly due to compromised cerebral vasodilatory response. Hypothesis: In adult SCD patients, cerebrovascular reactivity (CVR) and speed of vasodilatory response (tau) to a standardized vasodilatory stimulus, are reduced compared to normal subjects. Methods: Functional brain imaging performed as part of routine care in adult SCD patients without known large vessel cerebral vasculopathy was reviewed retrospectively. CVR was calculated as the change in CBF measured as the blood-oxygenation-level-dependent (BOLD)-magnetic resonance imaging signal, in response to a standard vasoactive stimulus of carbon dioxide (CO2). The tau corresponding to the best fit between the convolved end-tidal partial pressures of CO2 and BOLD signal was defined as the speed of vascular response. CVR and tau were normalized using a previously generated atlas of 42 healthy controls. Results: Fifteen patients were included. CVR was reduced in grey and white matter (mean Z-score for CVR -0.5 [-1.8 to 0.3] and -0.6 [-2.3 to 0.7], respectively). Tau Z-scores were lengthened in grey and white matter (+0.9 [-0.5 to 3.3] and +0.8 [-0.7 to 2.7], respectively). Hematocrit was the only significant independent predictor of CVR on multivariable regression. Conclusion: Both measures of cerebrovascular health (CVR and tau) in SCD patients were attenuated compared to normal controls. These findings show that CVR represents a promising tool to assess disease state, stroke risk, and therapeutic efficacy of treatments in SCD and merits further investigation.

Thromboprophylaxis Reduced Venous Thromboembolism in Sickle Cell Patients with Central Venous Access Devices: A Retrospective Cohort Study.

Sickle cell disease (SCD) induces a chronic prothrombotic state. Central venous access devices (CVADs) are commonly used for chronic transfusions and iron chelation in this population. CVADs are an additional venous thromboembolism (VTE) risk factor. The role of thromboprophylaxis in this setting is uncertain. The objectives are: (1) to determine whether thromboprophylaxis reduces VTE risk in SCD patients with CVAD and (2) to explore characteristics associated with VTE risk. We identified adults with SCD and CVAD intended for chronic use (≥3 months) at two comprehensive SCD centers. Thromboprophylaxis presence; type; intensity; and patient-, catheter-, and treatment-related VTE risk factors were recorded. Among 949 patients, 49 had a CVAD (25 without and 24 with VTE prophylaxis). Thromboprophylaxis type and intensity varied widely. Patients without thromboprophylaxis had higher VTE rates (rate ratio (RR) = 4.0 (95% confidence interval: 1.2−12.6), p = 0.02). Hydroxyurea was associated with lower VTE rates (RR = 20.5 (6.4−65.3), p < 0.001). PICC lines and Vortex and Xcela Power implantable devices were associated with higher rates compared with Port-a-Cath (RR = 5.8 (1.3−25.9), p = 0.02, and RR = 58.2 (15.0−225.0), p < 0.001, respectively). Thromboprophylaxis, hydroxyurea, and CVAD subtype were independently associated with VTE. The potentially protective role of thromboprophylaxis and hydroxyurea for VTE prevention in patients with SCD and CVAD merits further exploration.

COVID-19 and Sickle Cell Disease in the Province of Quebec, Canada: Outcomes after Two Years of the Pandemic.

BACKGROUND: Patients with sickle cell disease (SCD) are considered at higher risk of severe COVID-19 infection. However, morbidity and mortality rates are variable among countries. To date, there are no published reports that document outcomes of SCD patients with COVID-19 in Canada. METHODS: A web-based registry was implemented in June 2020 capturing outcomes of SCD patients with COVID-19 from March 2020 to April 2022 and comparing them to the general population of Quebec, Canada. RESULTS: After 24 months of the pandemic, 185 SCD patients with confirmed SARS-CoV-2 infection were included in the registry. Overall, the population was young (median age 12 years old) and had few comorbidities. No deaths were reported. Risk of hospitalization and admission to intensive care unit (ICU) because of COVID-19 was higher in patients with SCD than in the general population (relative risks (RR) 5.15 (95% confidence interval (95% CI) 3.84-6.91), p ˂ 0.001 and 4.56 (95% CI 2.09-9.93) p ˂ 0.001). A history of arterial hypertension or acute chest syndrome in the past 12 months was associated with a higher risk of severe disease (RR = 3.06 (95% CI 1.85-5.06) p = 0.008 and 2.27 (95% CI 1.35-3.83) p = 0.01). Hospitalized patients had lower hemoglobin F than non-hospitalized patients (12% vs. 17%, p = 0.02). For those who had access to vaccination at the time of infection, 25 out of 26 patients were adequately vaccinated and had mild disease. CONCLUSIONS: The SCD population is at higher risk of severe disease than the general population. However, we report favorable outcomes as no deaths occurred. Registries will continue to be critical to document the impact of novel COVID-19 specific therapy and vaccines for the SCD population.

Screening for Cognitive Dysfunction Using the Rowland Universal Dementia Assessment Scale in Adults With Sickle Cell Disease.

Importance: Adults with sickle cell disease (SCD) disproportionally experience early cognitive decline; however, guidance on the optimal screening strategy for cognitive dysfunction is lacking, and several available tools are biased by language, educational level, socioeconomic status, and race/ethnicity. The Rowland Universal Dementia Assessment Scale (RUDAS) was specifically designed for cognitive screening in multicultural populations. Objective: To ascertain the prevalence of suspected dementia in adults with SCD using the RUDAS, and to identify whether age, sex, educational level, several biological variables, and SCD complications were associated with RUDAS scores. Design, Setting, and Participants: This multicenter, bilingual, cross-sectional study was conducted in 2 SCD comprehensive care centers in Canada (Centre Hospitalier de l'Université Montréal in Montréal and University Health Network in Toronto). Participants were adults aged 18 years or older and were enrolled in the study between July 1, 2018, and July 30, 2019. All outpatients were eligible and offered study participation, unless they had an acute medical condition that required inpatient care or they were unable to follow study instructions. Interventions: The RUDAS was administered by trained personnel in either French or English, according to the patient's language preference. A questionnaire on social determinants of health was also administered, and participants underwent screening for anxiety and depression. Main Outcomes and Measures: Proportion of participants with RUDAS scores that were suggestive of dementia and the RUDAS score. Any score lower than 23 points was suggestive of dementia, a score between 23 and 27 points indicated a possible association with mild neurocognitive disorder, and a score higher than 27 points was normal. Results: A total of 252 adult patients with SCD were included (136 women [54.0%]; mean [range] age, 34.8 [18-75] years). Overall, 29 patients (11.5%) had RUDAS scores that were suggestive of dementia, and this proportion increased with age (15 [8.7%] in the 18-39 years age group, 10 [14.5%] in the 40-59 years age group, and 4 [36.4%] in the ≥60 years age group). The RUDAS scores were not associated with sex, language, SCD genotype, and SCD complications. The highest level of education was significantly associated with the RUDAS score; however, the association was small (η2 = 0.02; 95% CI, 0.00-0.07; P = .02). In a multivariable analysis, lower glomerular filtration rate (r = 0.40; 95% CI, 0.29-0.50; P < .001) and increasing age (r = -0.37; 95% CI, -0.47 to -0.26; P < .001), but not SCD genotype or disease severity, were associated with lower RUDAS scores. Conclusions and Relevance: This study found that using the RUDAS revealed a high prevalence of suspected dementia in adult patients with SCD that was associated with worsening kidney function and age. Cognition should be screened in all adult patients with SCD, regardless of age, disease severity, and SCD genotype; further validation of the RUDAS is ongoing.

Hypo-osmolar stress induces p75NTR expression by activating Sp1-dependent transcription.

Injury-induced expression of the p75 neurotrophin receptor (p75NTR) in the CNS facilitates neuronal apoptosis and prevents neuronal regrowth, but the mechanisms regulating p75NTR expression are poorly characterized. In this study, we showed that hypo-osmolarity induces p75NTR expression in primary neurons, and, using a comparative genomics approach, we identified conserved elements in the 25 kb upstream sequences of the rat, mouse, and human p75NTR genes. We found that only one of these, a proximal region rich in Sp1 sites, responds to changes in hypo-osmolarity. We then showed that Sp1 DNA binding activity is increased in cells exposed to hypo-osmolarity, established that hypo-osmolarity enhanced Sp1 binding to the endogenous p75NTR promoter, and showed that Sp1 is required for p75NTR expression induced by hypo-osmolarity. We examined how Sp1 is regulated to effect these changes and established that Sp1 turnover is strongly inhibited by hypo-osmolarity. We propose that stress-induced Sp1 accumulation that results from reductions in Sp1 turnover rate contributes to injury-induced gene expression.