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Insertion of venous access devices (VAD) is usually considered a procedure with low risk of bleeding. Nonetheless, insertion of some devices is invasive enough to be associated with bleeding, especially in patients with previous coagulopathy or in treatment with antithrombotic drugs for cardiovascular disease. The current practices of platelet/plasma transfusion in coagulopathic patients and of temporary suspension of the antithrombotic treatment before VAD insertion are based on local policies and are often inadequately supported by evidence, since many of the clinical studies on this topic are not recent and are not of high quality. Furthermore, the protocols of antithrombotic treatment have changed during the last decade, after the introduction of new oral anticoagulant drugs. Though some guidelines address some of these issues in relation with specific procedures (port insertion, etc.), no evidence-based document covering all the aspects of this clinical problem is currently available. Thus, the Italian Group of Venous Access Devices (GAVeCeLT) has decided to develop a consensus on the management of antithrombotic treatment and bleeding disorders in patients requiring VADs. After a systematic review of the available evidence, the panel of the consensus (which included vascular access specialists, surgeons, intensivists, anesthetists, cardiologists, vascular medicine experts, nephrologists, infective disease specialists, and thrombotic disease specialists) has structured the final recommendations as detailed answers to three sets of questions: (1) which is an appropriate classification of VAD-related procedures based on the specific bleeding risk? (2) Which is the appropriate management of the patient with bleeding disorders candidate to VAD insertion/removal? (3) Which is the appropriate management of the patient on antithrombotic treatment candidate to VAD insertion/removal? Only statements reaching a complete agreement were included in the final recommendations, and all recommendations were offered in a clear and synthetic list, so to be easily translated into clinical practice.

Background: Multi-drug resistant organisms (MDRO) are an emerging health problem with an important impact on clinical outcome in Intensive Care Units (ICUs) and immunocompromised patients. Conversely, the role of MDRO colonization in Internal Medicine is less clear. The objective of our study is to evaluate the clinical impact (namely sepsis development, in-hospital and 30-days mortality, and re-hospitalization) of MDRO colonization in Internal Medicine. Methods: Patients admitted to our Internal Medicine Unit between January 2019 and March 2020 were potentially includible. Outcomes in patients with a positive rectal swab for MDRO (RS+) and in patients without a RS+ were compared. Results of the multivariate analyses were expressed as Odds Ratios (ORs) and the corresponding 95% Confidence Interval (CI). Results: In a cohort of 2147 patients, 77 patients with RS+ were consecutively identified; 377 patients with a rectal swab negative for MDRO were randomly selected from the same cohort (five for each patient with RS+). At the multivariate analysis, RS+ was associated with an increased risk of sepsis development during hospitalization (OR 4.18; 95% CI, 1.99–8.78) and with death or re-hospitalization at 30 days (OR 4.79; 95% CI, 2.79–8.23), whereas RS+ did not appear to be associated with death during hospitalization or need for ICU transfer. Conclusions: Our results suggest for the first time a prognostic role for RS+ in Internal Medicine. Thus, assessment of rectal swab at hospital admission appears useful even in this setting. However, larger prospective studies and a cost–benefit analysis are needed to confirm our preliminary findings.

Background: The ideal intraprocedural method for tip location during insertion of femorally inserted central catheters (FICCs) is still a matter of debate. When the catheter tip is meant to be in the right atrium or in the supradiaphragmatic inferior vena cava (IVC), tip location by either intracavitary electrocardiography or transthoracic echocardiography may be accurate and easy to perform. When the catheter tip is planned to be placed in the subdiaphragmatic IVC, fluoroscopy—though inaccurate and unsafe—has been regarded as the only option for intraprocedural tip location. Methods: We have investigated prospectively the applicability and feasibility of transhepatic ultrasound as intraprocedural method for assessing the location of the catheter tip in the subdiaphragmatic tract of IVC, during FICC insertion. Results: We enrolled 169 consecutive patients undergoing FICC insertion by ultrasound guided puncture of the superficial femoral vein. In 165 out of 169 patients, the subdiaphragmatic IVC was visualized by the transhepatic ultrasound view. In all cases of IVC visualization, the catheter tip could be identified by ultrasound, either directly (direct evidence of the tip inside the vein) or indirectly (enhanced visualization of the tip after “bubble test”). There was no immediate or early complication, and very few late complications. Conclusion: The intraprocedural method of tip location of FICCs by transhepatic ultrasound was applicable in 97.6% of cases and feasible in 100%. When the position of the catheter tip is planned to be in the subdiaphragmatic IVC, this method of tip location is accurate, safe, and inexpensive, and should be considered as an alternative to fluoroscopy.

BACKGROUND: A remarkably high incidence of venous thromboembolism (VTE) has been reported among critically ill patients with COVID-19 assisted in the intensive care unit (ICU). However, VTE burden among non-ICU patients hospitalized for COVID-19 that receive guideline-recommended thromboprophylaxis is unknown. OBJECTIVES: To determine the incidence of VTE among non-ICU patients hospitalized for COVID-19 that receive pharmacological thromboprophylaxis. METHODS: We performed a systematic screening for the diagnosis of deep vein thrombosis (DVT) by lower limb vein compression ultrasonography (CUS) in consecutive non-ICU patients hospitalized for COVID-19, independent of the presence of signs or symptoms of DVT. All patients were receiving pharmacological thromboprophylaxis with either enoxaparin or fondaparinux. RESULTS: The population that we screened consisted of 84 consecutive patients, with a mean age of 67.6 ± 13.5 years and a mean Padua Prediction Score of 5.1 ± 1.6. Seventy-two patients (85.7%) had respiratory insufficiency, required oxygen supplementation, and had reduced mobility or were bedridden. In this cohort, we found 10 cases of DVT, with an incidence of 11.9% (95% confidence interval [CI] 4.98-18.82). Of these, 2 were proximal DVT (incidence rate 2.4%, 95% CI -0.87-5.67) and 8 were distal DVT (incidence rate 9.5%, 95% CI 3.23-5.77). Significant differences between subjects with and without DVT were D-dimer > 3000 µg/L (P

Abnormalities in arterial versus venous endothelial cell identity and dysregulation of angiogenesis are deemed important in the pathophysiology of brain arteriovenous malformations (AVMs). The Sonic hedgehog (Shh) pathway is crucial for both angiogenesis and arterial versus venous differentiation of endothelial cells, through its dual role on the vascular endothelial growth factor/Notch signaling and the nuclear orphan receptor COUP-TFII. In this study, we show that Shh, Gli1 (the main transcription factor of the Shh pathway), and COUP-TFII (a target of the non-canonical Shh pathway) are aberrantly expressed in human brain AVMs. We also show that implantation of pellets containing Shh in the cornea of Efnb2/LacZ mice induces growth of distinct arteries and veins, interconnected by complex sets of arteriovenous shunts, without an interposed capillary bed, as seen in AVMs. We also demonstrate that injection in the rat brain of a plasmid containing the human Shh gene induces the growth of tangles of tortuous and dilated vessels, in part positive and in part negative for the arterial marker αSMA, with direct connections between αSMA-positive and -negative vessels. In summary, we show that the Shh pathway is active in human brain AVMs and that Shh-induced angiogenesis has characteristics reminiscent of those seen in AVMs in humans.

Upper-extremity deep vein thrombosis (UEDVT) accounts for about 5-10% of all cases of deep vein thrombosis (DVT). It is often associated with cancer and/or presence of a central venous catheter (CVC), but it may also occur in the absence of these favoring conditions. The safety and efficacy of using direct oral anticoagulants (DOACs) in subjects with UEDVT has not been systematically evaluated and the only data available in the literature derive from anecdotal evidence, analysis of registries, and small single-centre studies. In addition, a specific analysis of UEDVT not associated with cancer and/or CVC has never been made. In this study, we specifically focused on patients with no cancer and without a CVC who were diagnosed with a first episode of UEDVT and were treated with a DOAC. We studied 61 patients, treated in six Italian centres between January 2014 and December 2018. Treatment lasted at least 3 months in all patients. In terms of efficacy, no recurrence of thrombosis or pulmonary embolism were recorded, while Doppler ultrasonography, performed after at least three months of treatment, documented in all cases either partial or complete recanalization of obstructed veins. In terms of safety, no cases of major bleedings were recorded. This is the only series available in the literature of patients treated with DOACs for UEDVT not associated with cancer and/or CVC. This small multicenter real world experience supports the concept that DOACs might be safe and effective for treating UEDTV. Further studies are required to better understand the role of DOACs in these patients.

An 18-year-old man presented to our hospital with muscular pain, diffuse petechiae, spontaneous thigh ecchymosis, edema and pain of the right knee, bilateral pretibial subcutaneous nodules, and gingival hypertrophy and hemorrhage. His history was positive for a mixed anxiety-depressive disorder and a restrictive diet caused by self-diagnosed food allergies. Skin lesions appeared like hyperkeratotic papules with coiled hairs and perifollicular hemorrhages. A diagnosis of scurvy was made upon demonstration of low serum levels of ascorbic acid. An allergy evaluation found cross-reactivity between pollens and food, related to the presence of panallergens. Moreover, we found that our patient was also affected by celiac disease. In conclusion, scurvy should be considered in the differential diagnosis of patients with petechiae and ecchymosis, especially when food restriction, malabsorption, or psychiatric disorders are present.

Whether antithrombotic treatment is safe and/or affects the risk of intracranial bleeding in subjects with sporadic brain arteriovenous malformations (AVMs) is unknown. We conducted a retrospective analysis on the use of antithrombotics among patients affected by brain AVMs in follow-up at our institution. Attention was paid to the type of antithrombotic drug (either antiplatelets or anticoagulants), current or past use, dosage, and duration of treatment. Several clinical and angioarchitectural features of brain AVMs were also taken into consideration. The association between the use of antithrombotics and haemorrhagic onset was analyzed. A total of 77 patients were included in this study. Among them, ten patients were taking antithrombotic drugs at the time of AVM diagnosis. The rate of haemorrhagic onset was not significantly different between subjects who were and were not taking antithrombotic drugs (40 vs 55.2%, p = ns). Among the many clinical and angioarchitectural features analyzed, the only parameter that showed a statistically significant association with haemorrhagic onset was the size of the nidus. Patients who took antithrombotic treatments after being diagnosed with a brain AVM did not show an increased rate of intracranial haemorrhage over time considering a mean follow-up 4 years. In our study, antithrombotic treatment was not associated with increased intracranial bleeding among subjects with brain AVMs. In the presence of a strong clinical indication, antiplatelet and anticoagulant medications should not be denied a priori to patients with brain AVMs. Studies on larger populations are necessary to confirm these data.

Hedgehog (Hh) proteins are prototypical morphogens known to regulate epithelial/mesenchymal interactions during embryonic development. In addition to its pivotal role in embryogenesis, the Hh signaling pathway may be recapitulated in post-natal life in a number of physiological and pathological conditions, including ischemia. This review highlights the involvement of Hh signaling in ischemic tissue regeneration and angiogenesis, with particular attention to the heart, the brain, and the skeletal muscle. Updated information on the potential role of the Hh pathway as a therapeutic target in the ischemic condition is also presented.

Unusual site deep vein thrombosis (USDVT) is an uncommon form of venous thromboembolism with heterogeneous signs and symptoms, unknown rate of pulmonary embolism (PE), and poorly defined risk factors. We conducted a retrospective analysis of 107 consecutive cases of USDVTs, discharged from our University Hospital over a period of 2 years. Patients were classified based on the site of thrombosis and distinguished between patients with cerebral vein thrombosis, jugular vein thrombosis, thrombosis of the deep veins of the upper extremities, and abdominal vein thrombosis. We found statistically significant differences between groups in terms of age ( P < .0001) and gender distribution ( P < .05). We also found that the rate of symptomatic patients was significantly different between groups ( P < .0001). Another interesting finding was the significant difference between groups in terms of rate of PE ( P < .01). Finally, we found statistically significant differences between groups in terms of risk factors for thrombosis, in particular cancer ( P < .01). Unprovoked cases were differently distributed among groups ( P < .0001). This study highlights differences between patients with USDVT, which depend on the site of thrombosis, and provides data which might be useful in clinical practice.

Hedgehog (Hh) proteins are prototypical morphogens known to regulate epithelial/mesenchymal interactions during embryonic development. In addition to its pivotal role in embryogenesis, the Hh signaling pathway may be recapitulated in post-natal life in a number of physiological and pathological conditions, including ischemia. This review highlights the involvement of Hh signaling in ischemic tissue regeneration and angiogenesis, with particular attention to the heart, the brain, and the skeletal muscle. Updated information on the potential role of the Hh pathway as a therapeutic target in ischemic condition is also presented.

Sonic hedgehog (Shh) is a prototypical angiogenic agent with a crucial role in the regulation of angiogenesis. Experimental studies have shown that Shh is upregulated in response to ischemia. Also, Shh may be found on the surface of circulating microparticles (MPs) and MPs bearing Shh (Shh + MPs) have shown the ability to contribute to reparative neovascularization after ischemic injury in mice. The goal of this study was to test the hypothesis that, in humans with peripheral artery disease (PAD), there is increased number of circulating Shh + MPs. This was done by assessing the number of Shh + MPs in plasma of patients with PAD and control subjects without PAD. We found significantly higher number of Shh + MPs in plasma of subjects with PAD, compared to controls, while the global number of MPs&mdash, produced either by endothelial cells, platelets, leukocytes, and erythrocytes&mdash, was not different between PAD patients and controls. We also found a significant association between the number of Shh + MPs and the number of collateral vessels in the ischemic limbs of PAD patients. Interestingly, the concentration of Shh protein unbound to MPs&mdash, which was measured in MP-depleted plasma&mdash, was not different between subjects with PAD and the controls, indicating that, in the setting of PAD, the call for Shh recapitulation does not lead to secretion of protein into the blood but to binding of the protein to the membrane of MPs. These findings provide novel information on Shh signaling during ischemia in humans, with potentially important biological and clinical implications.

Background: Microvascular obstruction (MVO) after primary percutaneous coronary intervention (pPCI) leads to higher incidence of both early and late complications. A number of single nucleotide polymorphisms in 9p21 chromosome have been shown to affect angiogenesis in response to ischaemia. In particular, Rs1333040 with its three genotypic vriants C/C, T/C and T/T might influence the occurrence of MVO after pPCI. Methods: We enrolled ST-elevation myocardial infarction (STEMI) patients undergoing pPCI. The Rs1333040 polymorphism was evaluated by polymerase chain reaction-restriction fragment length polymorphism using restriction endonucleases (Bsml). Two expert operators unaware of the patients’ identity performed the angiographic analysis; collaterals were assessed applying Rentrop’s classification. Angiographic MVO was defined as a post-pPCI Thrombolysis In Myocardial Infarction (TIMI)Results: Among our 133 STEMI patients (mean age 63 ± 11 years, men 72%), 35 (26%) and 53 (40%) respectively experienced angiographic or electrocardiographic MVO. Angiographic and electrocardiographic MVO were different among the three variants ( p= 0.03 and p=0.02 respectively). In particular, T/T genotype was associated with a higher incidence of both angiographic and electrocardiographic MVO compared with C/C genotype ( p=0.04 and p=0.03 respectively). Moreover, Rentrop score Conclusion: Rs1333040 polymorphism genetic variants portend different MVO incidence. In particular, T/T genotype is related to angiographic and electrocardiographic MVO and to worse collaterals towards the culprit artery.

Circulating microparticles (MPs) are novel potential biomarkers in cancer patients. Their role in hepatocellular carcinoma (HCC) is under intensive investigation. In this study, we tested the hypothesis that MPs expressing the antigen HepPar1 are increased in the blood of subjects with HCC and may serve as markers of early recurrence after liver resection (LR). We studied 15 patients affected by HCC undergoing LR, and used flow cytometry to assess the number of circulating HepPar1+ MPs. Ten subjects without HCC (five with liver cirrhosis and five with healthy livers) were used as controls. After LR, HCC patients underwent a follow-up to check for early recurrence, which occurred in seven cases. The number of circulating HepPar1+ MPs was significantly higher in subjects affected by HCC, compared to individuals without cancer (p < 0.01). We also found that, among HCC patients, the number of circulating HepPar1+ MPs, measured before LR, was significantly higher in those who displayed early recurrence compared to those without recurrence (p = 0.02). Of note, other types of circulating MPs, such as those derived from endothelial cells (CD144+) or those produced by the activated endothelium (CD144+/CD62+), were not associated with HCC, nor could they predict HCC recurrence. HepPar1+ MPs deserve further investigation as novel biomarkers of disease and prognosis in HCC patients.

Background Single nucleotide polymorphisms (SNPs) on chromosome 9p21 have been recently associated with intracranial aneurysms and stroke. In this study, we tested the association between the rs1333040C>T polymorphism on the 9p21 locus and sporadic brain arteriovenous malformations (BAVMs). Methods We studied 78 patients with sporadic BAVMs and 103 unaffected controls. Genomic DNA was isolated from peripheral blood and the rs1333040C>T polymorphism was assessed by PCR–restriction fragment length polymorphism using the BsmI restriction endonuclease. Results We found that the distribution of the three genotypes (TT/TC/CC) of the rs1333040 polymorphism was significantly different between cases and controls (p=0.02). Using dominant, recessive and additive genetic models, we found that the TT genotype and the T allele were significantly more common in the BAVM group than in controls. We also evaluated whether the rs1333040 polymorphism was associated with prototypical angio-architectural features of BAVMs (such as nidus size, venous drainage pattern and Spetzler–Martin grading) and with the occurrence of seizures and bleeding. We detected a significant association between the homozygous T allele in the recessive model and BAVMs with a nidus >4 cm in diameter. Deep venous drainage was significantly more frequent among subjects carrying at least one T allele in the dominant model. Patients with seizures showed a significant association with the TT genotype and the T allele in all genetic models examined whereas those who experienced intracranial bleeding showed a significant association with the T allele in the trend model. Conclusions This is the first study demonstrating an association between an SNP of the 9p21 region and sporadic BAVMs. Our results emphasise the relevance of this chromosomal locus as a common risk factor for various forms of cerebrovascular diseases.

In polycythemia vera, gender has recently been shown to influence the JAK2(V617F) allele burden, but its effect on the disease phenotype is unknown. This issue was investigated using the database of the European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) Study. The ECLAP Study recruited 1,638 polycythemic subjects and followed for 2.7 ± 1.3 years. At study entry, men, compared to women, had a higher prevalence of myocardial infarction (11.3 vs. 5.8%; P0.0001) and peripheral arterial disease (6.1 vs. 2.9%; P0.05) while a history of venous thrombosis was more common in women (11.4 vs. 7.9%, P = 0.016). Among 234 venous thrombosis, there were 39 splanchnic vein thromboses (33 extra-hepatic portal vein thromboses and 6 Budd-Chiari syndromes). Most of these events occurred as an early disease presentation in young female subjects. Women, compared to men, had higher platelet counts (average value 430 ± 213 vs. 375 ± 201 × 10(9)/L; P0.0001) and lower hematocrits (0.46 ± 0.06 vs. 0.48 ± 0.06 l/l; P0.0001). Cholesterol plasma level, available in 995 subjects (61%), was lower in male patients (180.8 ± 43.1 vs. 196 ± 46.6 mg/dl; P0.0001). During follow-up there were 205 major thromboses confirming an high incidence of myocardial infarction in men although not statistically significant (1.2 vs. 0.6 cases per 100 person-years; P0.05). These data show several gender-related differences both in the thrombotic diathesis and in the prevalence of vascular risk factors of PV patients.

Microparticles (MPs) are submicron vesicles shed from various cell types upon activation, stimulation, and death. Activated platelets are an important source of circulating MPs in subjects with inflammatory diseases, including Crohn&rsquo, s disease (CD). Angiogenesis is a hallmark of inflammation in CD and plays an active role in sustaining disease progression, while targeting angiogenesis may be an effective approach to block colitis. In this study, we analyzed the angiogenic content of the MPs produced by activated platelets in subjects with CD. We also evaluated whether the angiogenic signal carried by these MPs was functionally active, or able to induce angiogenesis. We found that, in subjects with CD, MPs produced by activated platelets contain significantly higher levels of angiogenic mRNAs, such as epidermal growth factor (EGF), platelet-derived growth factor-&alpha, (PDGF&alpha, ), fibroblast growth factor (FGF-2), and angiopoietin-1 (ANGPT1), compared to MPs isolated from control subjects. They also contain significantly higher levels of prototypical angiogenic proteins, including vascular endothelial growth factor (VEGF), angiopoietin-1, endoglin, endothelin-1, pentraxin 3, platelet factor-4, plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloproteinases-1 (TIMP-1), and thrombospondin 1. The protein content of these MPs is functionally active, since it has the ability to induce a robust angiogenic process in an endothelial cell/interstitial cell co-culture in vitro assay. Our results reveal a potential novel mechanism through which the angiogenic signal is delivered in subjects with CD, with potentially important clinical and therapeutic implications.

Background: The chromosomal locus 9p21 is a novel genetic marker for a variety of cardiovascular and cerebrovascular diseases. In a recent study, we have demonstrated an association between the single nucleotide polymorphism (SNP) rs1333040C>T on chromosome 9p21 and sporadic brain arteriovenous malformations (BAVMs). Here, we extended our analysis to an additional SNP on chromosome 9p21 (rs7865618A>G) and increased our sample size including BAVMs from two different Italian neurosurgical centers. Methods: We studied 206 patients with sporadic BAVMs and 171 unaffected controls. Genomic DNA was isolated from peripheral blood and the rs1333040C>T and rs7865618A>G polymorphisms were assessed by PCR-RFLP using the BsmI and MspI restriction endonucleases, respectively. For each SNP, we performed dominant, recessive, and additive genetic models. Results: The distribution of the three possible genotypes of rs1333040 (TT, TC and CC) was statistically different between cases and controls (p = 0.0008). The TT genotype was significantly associated with BAVMs both in the dominant (p = 0.013) and recessive (p = 0.012) models. The T allele was significantly associated with BAVMs in the additive model (p = 0.002). Also the distribution of the three possible genotypes of rs7865618 (GG, AG and AA) was statistically different between cases and controls (p = 0.005), and the GG genotype and G allele were significantly associated with BAVMs in the dominant (p = 0.032), recessive (p = 0.007), and additive models (p = 0.009). We also detected a significant association between BAVMs with large nidus size and the GG genotype and G allele of rs7865618 and the TT genotype of rs1333040. A deep venous drainage was instead associated with the TT genotype of the rs1333040 and the GG genotype of the rs7865618. The occurrence of bleeding was associated with the TT genotype and T allele of rs1333040, while the presence of seizures appeared associated with the GG genotype of rs7865618. Conclusions: SNPs of the 9p21 region, in addition to be genetic markers for coronary artery disease, stroke, and intracranial aneurysms, are associated with sporadic BAVMs. These results extend and strengthen the role of the 9p21 chromosomal region as a common risk factor for cerebrovascular diseases.

The Hedgehog (Hh) pathway is a crucial regulator of muscle development during embryogenesis. We have previously demonstrated that Sonic hedgehog (Shh) regulates postnatal myogenesis in the adult skeletal muscle both directly, by acting on muscle satellite cells, and indirectly, by promoting the production of growth factors from interstitial fibroblasts. Here, we show that in mdx mice, the murine equivalent of Duchenne muscular dystrophy in humans, progression of the dystrophic pathology corresponds to progressive inhibition of the Hh signaling pathway in the skeletal muscle. We also show that the upregulation of the Hh pathway in response to injury and during regeneration is significantly impaired in mdx muscle. Shh treatment increases the proliferative potential of satellite cells isolated from the muscles of mdx mice. This treatment also increases the production of proregenerative factors, such as insulin-like growth factor-1 and vascular endothelial growth factor, from fibroblasts isolated from the muscle of mdx mice. In vivo, overexpression of the Hh pathway using a plasmid encoding the human Shh gene promotes successful regeneration after injury in terms of increased number of proliferating myogenic cells and newly formed myofibers, as well as enhanced vascularization and decreased fibrosis.

Sonic hedgehog (Shh) is a morphogen regulating muscle development during embryogenesis. We have shown that the Shh pathway is postnatally recapitulated after injury and during regeneration of the adult skeletal muscle and regulates angiogenesis and myogenesis after muscle injury. Here, we demonstrate that in 18-month-old mice, there is a significant impairment of the upregulation of the Shh pathway that physiologically occurs in the young skeletal muscle after injury. Such impairment is even more pronounced in 24-month-old mice. In old animals, intramuscular therapy with a plasmid encoding the human Shh gene increases the regenerative capacities of the injured muscle, in terms of Myf5-positive cells, regenerating myofibers, and fibrosis. At the molecular level, Shh treatment increases the upregulation of the prototypical growth factors, insulin-like growth factor-1 and vascular endothelial growth factor. These data demonstrate that Shh increases regeneration after injury in the muscle of 24-month-old mice and suggest that the manipulation of the Shh pathway may be useful for the treatment of muscular diseases associated with aging.