Use of cryopreserved human amniotic membrane in the treatment of skin ulcers secondary to calciphylaxis.

Calciphylaxis is a rare condition characterized by skin ulceration and necrosis as a result of vascular calcification of the small and medium blood vessels of skin and subcutaneous tissues. It mainly occurs in patients with advanced chronic kidney disease and sometimes leads to complications with a fatal outcome. In this report, we describe the case of a 67-year-old male patient with end stage renal disease presenting painful skin ulcers on his lower limbs. The lesions had progressively grown and were associated to severe pain and decreased quality of life. The ulcers did not respond to conventional treatments and the patient underwent skin biopsy of these lesions obtaining anatomopathological findings compatible with calciphylaxis. In this report, we present an innovative treatment for skin ulcers secondary to calciphylaxis using cryopreserved amniotic membrane (AM) as a dressing in order to promote epithelialization of the wounds. After four applications, healing of the main ulcer and reduction in pain was achieved. In summary, applying cryopreserved AM probed to be a promising strategy to reduce pain and to enhance epithelialization and healing of chronic non-responsive ulcers in calciphylaxis.

Cryopreserved amniotic membrane in the treatment of diabetic foot ulcers: a case series.

OBJECTIVE: The amniotic membrane (AM) is a tissue with low immunogenity and high therapeutic potential due to its anti-inflammatory, anti-fibrotic and antimicrobial effects. This paper describes the use of cryopreserved amniotic membrane allografts to treat diabetic foot ulcers (DFUs) in patients with diabetes. METHOD: In this case series, AM was processed to obtain a final medicinal product: cryopreserved amniotic membrane. cryopreserved AM was applied every 7-10 days until total epithelialisation of the DFUs. RESULTS: A total of 14 patients with DFUs (median size: 12.30cm, (range: 0.52-42.5cm2) were treated and followed up until complete closure (median time: 20 weeks, range: 7-56 weeks). Patients received 4-40 AM applications. All patients in this study achieved complete epithelialisation of the wound. No adverse events were observed. CONCLUSION: AM is a feasible and safe treatment in complex DFUs. Furthermore, the treatment is successful in achieving epithelialisation of long-evolution, unhealed wounds resistant to conventional therapies.

Cerebral autoregulation and symptoms of orthostatic hypotension in familial dysautonomia.

Familial dysautonomia is an inherited autonomic disorder with afferent baroreflex failure. We questioned why despite low blood pressure standing, surprisingly few familial dysautonomia patients complain of symptomatic hypotension or have syncope. Using transcranial Doppler ultrasonography of the middle cerebral artery, we measured flow velocity (mean, peak systolic, and diastolic), area under the curve, pulsatility index, and height of the dictrotic notch in 25 patients with familial dysautonomia and 15 controls. In patients, changing from sitting to a standing position, decreased BP from 124 ± 4/64 ± 3 to 82 ± 3/37 ± 2 mmHg (p < 0.0001, for both). Despite low BP, all patients denied orthostatic symptoms. Middle cerebral artery velocity fell minimally, and the magnitude of the reductions were similar to those observed in healthy controls, in whom BP upright did not fall. While standing, patients had a greater fall in cerebrovascular resistance (p < 0.0001), an increase in pulsatility (p < 0.0001), and a deepening of the dicrotic notch (p = 0.0010), findings all consistent with low cerebrovascular resistance. No significant changes occurred in controls. Patients born with baroreflex deafferentation retain the ability to buffer wide fluctuations in BP and auto-regulate cerebral blood flow. This explains how they can tolerate extremely low BPs standing that would otherwise induce syncope.

Increasing cutaneous afferent feedback improves proprioceptive accuracy at the knee in patients with sensory ataxia.

Hereditary sensory and autonomic neuropathy type III (HSAN III) features disturbed proprioception and a marked ataxic gait. We recently showed that joint angle matching error at the knee is positively correlated with the degree of ataxia. Using intraneural microelectrodes, we also documented that these patients lack functional muscle spindle afferents but have preserved large-diameter cutaneous afferents, suggesting that patients with better proprioception may be relying more on proprioceptive cues provided by tactile afferents. We tested the hypothesis that enhancing cutaneous sensory feedback by stretching the skin at the knee joint using unidirectional elasticity tape could improve proprioceptive accuracy in patients with a congenital absence of functional muscle spindles. Passive joint angle matching at the knee was used to assess proprioceptive accuracy in 25 patients with HSAN III and 9 age-matched control subjects, with and without taping. Angles of the reference and indicator knees were recorded with digital inclinometers and the absolute error, gradient, and correlation coefficient between the two sides calculated. Patients with HSAN III performed poorly on the joint angle matching test [mean matching error 8.0 ± 0.8° (±SE); controls 3.0 ± 0.3°]. Following application of tape bilaterally to the knee in an X-shaped pattern, proprioceptive performance improved significantly in the patients (mean error 5.4 ± 0.7°) but not in the controls (3.0 ± 0.2°). Across patients, but not controls, significant increases in gradient and correlation coefficient were also apparent following taping. We conclude that taping improves proprioception at the knee in HSAN III, presumably via enhanced sensory feedback from the skin.

Chewing-induced hypertension in afferent baroreflex failure: a sympathetic response?

NEW FINDINGS: What is the central question of this study? Our goal was to understand the autonomic responses to eating in patients with congenital afferent baroreflex failure, by documenting changes in blood pressure and heart rate with chewing, swallowing and stomach distension. What is the main finding and its importance? Patients born with lesions in the afferent baroreceptor pathways have an exaggerated pressor response to food intake. This appears to be a sympathetically mediated response, triggered by chewing, that occurs independently of swallowing or distension of the stomach. The chewing-induced pressor response may be useful as a counter-manoeuvre to prevent orthostatic hypotension in these patients. Familial dysautonomia (FD) is a rare genetic disease with extremely labile blood pressure resulting from baroreflex deafferentation. Patients have marked surges in sympathetic activity, frequently surrounding meals. We conducted an observational study to document the autonomic responses to eating in patients with FD and to determine whether sympathetic activation was caused by chewing, swallowing or stomach distension. Blood pressure and R-R intervals were measured continuously while chewing gum (n = 15), eating (n = 20) and distending the stomach by percutaneous endoscopic gastrostomy tube feeding (n = 9). Responses were compared with those of normal control subjects (n = 10) and of patients with efferent autonomic failure (n = 10) who have chronically impaired sympathetic outflow. In patients with FD, eating was associated with a marked but transient pressor response (P < 0.0001) and additional signs of sympathetic activation, including tachycardia, diaphoresis and flushing of the skin. Chewing gum evoked a similar increase in blood pressure that was higher in patients with FD than in control subjects (P = 0.0001), but was absent in patients with autonomic failure. In patients with FD, distending the stomach by percutaneous endoscopic gastrostomy tube feeding failed to elicit a pressor response. The results provide indirect evidence that chewing triggers sympathetic activation. The increase in blood pressure is exaggerated in patients with FD as a result of blunted afferent baroreceptor signalling. The chewing pressor response may be useful as a counter-manoeuvre to raise blood pressure and prevent symptomatic orthostatic hypotension in patients with FD.

Current treatments in familial dysautonomia.

INTRODUCTION: Familial dysautonomia (FD) is a rare hereditary sensory and autonomic neuropathy (type III). The disease is caused by a point mutation in the IKBKAP gene that affects the splicing of the elongator-1 protein (ELP-1) (also known as IKAP). Patients have dramatic blood pressure instability due to baroreflex failure, chronic kidney disease, and impaired swallowing leading to recurrent aspiration pneumonia, which results in chronic lung disease. Diminished pain and temperature perception result in neuropathic joints and thermal injuries. Impaired proprioception leads to gait ataxia. Optic neuropathy and corneal opacities lead to progressive visual loss. AREAS COVERED: This article reviews current therapeutic strategies for the symptomatic treatment of FD, as well as the potential of new gene-modifying agents. EXPERT OPINION: Therapeutic focus on FD is centered on reducing the catecholamine surges caused by baroreflex failure. Managing neurogenic dysphagia with effective protection of the airway passages and prompt treatment of aspiration pneumonias is necessary to prevent respiratory failure. Sedative medications should be used cautiously due to the risk of respiratory depression. Non-invasive ventilation during sleep effectively manages apneas and prevents hypercapnia. Clinical trials of compounds that increase levels of IKAP (ELP-1) are underway and will determine whether they can reverse or slow disease progression.

Stem cells derived from neonatal mouse kidney generate functional proximal tubule-like cells and integrate into developing nephrons in vitro.

We have recently shown that kidney-derived stem cells (KSCs) isolated from the mouse newborn kidney differentiate into a range of kidney-specific cell types. However, the functionality and integration capacity of these mouse KSCs remain unknown. Therefore, the main objectives of this study were (1) to determine if proximal tubule-like cells, generated in vitro from KSCs, displayed absorptive function typical of proximal tubule cells in vivo, and (2) to establish whether the ability of KSCs to integrate into developing nephrons was comparable with that of metanephric mesenchyme (MM), a transient population of progenitor cells that gives rise to the nephrons during kidney organogenesis. We found that proximal tubule-like cells generated in vitro from mouse KSCs displayed megalin-dependent absorptive function. Subsequently, we used a chimeric kidney rudiment culture system to show that the KSCs could generate proximal tubule cells and podocytes that were appropriately located within the developing nephrons. Finally, we compared the ability of KSCs to integrate into developing kidneys ex vivo with that of metanephric mesenchyme cells. We found that KSCs integrated into nascent nephrons to a similar extent as metanephric mesenchyme cells while both were excluded from ureteric bud branches. Our analysis of the behavior of the two cell types shows that some, but not all KSC characteristics are similar to those of the MM.

Integration potential of mouse and human bone marrow-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are a multipotent cell population which has been described to exert renoprotective and regenerative effects in experimental models of kidney injury. Several lines of evidence indicate that MSCs also have the ability to contribute to nephrogenesis, suggesting that the cells can be employed in stem cell-based applications aimed at de novo renal tissue generation. In this study we re-evaluate the capacity of mouse and human bone marrow-derived MSCs to contribute to the development of renal tissue using a novel method of embryonic kidney culture. Although MSCs show expression of some genes involved in renal development, their contribution to nephrogenesis is very limited in comparison to other stem cell types tested. Furthermore, we found that both mouse and human MSCs have a detrimental effect on the ex vivo development of mouse embryonic kidney, this effect being mediated through a paracrine action. Stimulation with conditioned medium from a mouse renal progenitor population increases the ability of mouse MSCs to integrate into developing renal tissue and prevents the negative effects on kidney development, but does not appear to enhance their ability to undergo nephrogenesis.

Differentiation of podocyte and proximal tubule-like cells from a mouse kidney-derived stem cell line.

In this study we have shown that the papilla of the mouse kidney contains a population of Pax2+ cells that are detectable from the early postnatal period through to adulthood. Lineage analysis suggests that some of these Pax2+ cells are derived from the metanephric mesenchyme, a population of progenitor cells that gives rise to the nephrons during kidney organogenesis. Here we describe a method for isolating and culturing the Pax2+ population, and demonstrate that some cells within this population are multipotent stem cells, as they are clonogenic and appear to undergo unlimited self-renewal. Further, under appropriate culture conditions, these stem cells can differentiate to generate renal cell types, such as podocyte- and proximal tubule-like cells, and are also able to generate nonrenal cell types, such as adipocytes and osteocytes. The availability of a kidney-derived multipotent stem cell line with the potential to generate podocytes and proximal tubule cells in culture will expedite progress in understanding the biology of these important renal cell types, and will be a useful tool in toxicological studies and drug discovery.

The potential of small chemical functional groups for directing the differentiation of kidney stem cells.

In the future, stem-cell-based therapies could offer new approaches to treat kidney disease and reduce the incidence of ESRD (end-stage renal disease), but, as yet, research in this area is only being conducted in rodents and it is not clear whether or when it could be applied to human patients. Drug therapies, on the other hand, have been very effective at delaying the progression of kidney disease, but, for various reasons, current drug regimes are not suitable for all patients. A greater understanding of the molecular mechanisms that underlie disease progression in chronic kidney disease could help to identify novel drug targets. However, progress in this area is currently hindered due to the lack of appropriate in vitro culture systems for important renal cell types, such as proximal tubule cells and podocytes. This problem could be overcome if it were possible to direct the differentiation of kidney stem cells to renal cell types in vitro. In the present review, we highlight the potential of surface gradients of small chemical functional groups to direct the differentiation of kidney stem cells.