Injectable chitosan hydrogel effectively controls lesion growth in a venous malformation murine model

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of intralesional injection of chitosan hydrogel (CH) combined with sodium tetradecyl sulfate (STS) to sclerose and embolize venous malformations (VMs) by comparison with 3% STS foam and placebo in a mouse model.

MATERIALS AND METHODS

Subcutaneous VMs were created by injecting HUVEC_TIE2-L914F cells, mixed with matrigel, into the back of athymic mice (Day [D] 0). After VM-like lesions were established at D10, 70 lesions were randomly assigned to one of six treatment groups (untreated, saline, 3% STS-foam, CH, 1% STS-CH, 3% STS-CH). For 3% STS-foam, the standard Tessari technique was performed. VMs were regularly evaluated every 2-3 days to measure lesion size until the time of collection at D30 (primary endpoint). At D30, VM lesions including the matrigel plugs were culled and evaluated by histological analysis to assess vessel size, chitosan distribution and endothelial expression. One-way analysis of variance (ANOVA) test was performed to compare quantitative variables with normal distribution, otherwise Kruskal-Wallis test followed by pairwise comparisons by a Wilcoxon rank sum test was performed.

RESULTS

All VMs were successfully punctured and injected. Six VMs injected with 3% STS-CH showed early skin ulceration with an extrusion of the matrigel plug and were excluded from final analysis. In the remaining 64 VMs, skin ulceration occurred on 26 plugs, resulting in the loss of three 3% STS-foam and one 1% STS-CH plugs. Both chitosan formulations effectively controlled growth of VMs by the end of follow-up compared to untreated or 3% STS-foam groups (P < 0.05). Vessel sizes were smaller with both CH formulations compared to untreated and saline groups (P < 0.05). Additionally, there were smaller vascular channels within the 1% STS-CH group compared to the 3% STS-foam group (P < 0.05).

CONCLUSION

Chitosan's ability to control the growth of VMs suggests a promising therapeutic effect that outperforms the gold standard (STS-foam) on several variables.

Sclerotherapy of lower limb veins: Indications, contraindications and treatment strategies to prevent complications - A consensus document of the International Union of Phlebology-2023

BACKGROUND

Sclerotherapy is a non-invasive procedure commonly used to treat superficial venous disease, vascular malformations and other ectatic vascular lesions. While extremely rare, sclerotherapy may be complicated by serious adverse events.

OBJECTIVES

To categorise contraindications to sclerotherapy based on the available scientific evidence.

METHODS

An international, multi-disciplinary panel of phlebologists reviewed the available scientific evidence and developed consensus where evidence was lacking or limited.

RESULTS

Absolute Contraindications to sclerotherapy where the risk of harm would outweigh any benefits include known hypersensitivity to sclerosing agents; acute venous thromboembolism (VTE); severe neurological or cardiac adverse events complicating a previous sclerotherapy treatment; severe acute systemic illness or infection; and critical limb ischaemia. Relative Contraindications to sclerotherapy where the potential benefits of the proposed treatment would outweigh the risk of harm or the risks may be mitigated by other measures include pregnancy, postpartum and breastfeeding; hypercoagulable states with risk of VTE; risk of neurological adverse events; risk of cardiac adverse events and poorly controlled chronic systemic illness. Conditions and circumstances where Warnings and Precautions should be considered before proceeding with sclerotherapy include risk of cutaneous necrosis or cosmetic complications such as pigmentation and telangiectatic matting; intake of medications such as the oral contraceptive and other exogenous oestrogens, disulfiram and minocycline; and psychosocial factors and psychiatric comorbidities that may increase the risk of adverse events or compromise optimal treatment outcomes.

CONCLUSIONS

Sclerotherapy can achieve safe clinical outcomes provided that (1) patient-related risk factors and in particular all material risks are (1a) adequately identified and the risk benefit ratio is clearly and openly discussed with treatment candidates within a reasonable timeframe prior to the actual procedure; (1b) when an individual is not a suitable candidate for the proposed intervention, conservative treatment options including the option of 'no intervention as a treatment option' are discussed; (1c) complex cases are referred for treatment in controlled and standardised settings and by practitioners with more expertise in the field; (1d) only suitable individuals with no absolute contraindications or those with relative contraindications where the benefits outweigh the risks are offered intervention; (1e) if proceeding with intervention, appropriate prophylactic measures and other risk-mitigating strategies are adopted and appropriate follow-up is organised; and (2) procedure-related risk factors are minimised by ensuring the treating physicians (2a) have adequate training in general phlebology with additional training in duplex ultrasound, procedural phlebology and in particular sclerotherapy; (2b) maintain their knowledge and competency over time and (2c) review and optimise their treatment strategies and techniques on a regular basis to keep up with the ongoing progress in medical technology and contemporary scientific evidence.

Skin necrosis following sclerotherapy. Part 1: Differential diagnosis based on classification of pathogenic mechanisms

Background: Tissue necrosis is a significant but uncommon complication of sclerotherapy. The pathogenic mechanisms of this often-debilitating complication have been poorly described in the literature.Purpose: To elucidate the pathological mechanisms, we propose a morphological approach to classify sclerotherapy-induced skin necrosis into two categories of round and stellate (star-like) necrosis.Research Design: Comprehensive literature review was conducted.Results: Round necrosis is typically caused by extravasation of sclerosants. It typically presents as an ulcer with smooth and non-geographic borders. Historically, extravasation has been cited as the main cause of sclerotherapy-related necrosis. While this may be the case with osmotic or irritant sclerosants, it is far less likely with the use of detergent agents particularly in the foam format.The more commonly encountered pattern of stellate necrosis is an ischaemic ulcer secondary to arterial/arteriolar occlusion. In contrast to round necrosis, stellate necrosis follows an intra-vascular injection of sclerosants such as an inadvertent intra-arterial injection. But more frequently, stellate necrosis may follow a perfectly executed intra-venous or intra-telangiectatic delivery of sclerosants. Several pathogenic pathways can be considered. The physiologic response of veno-arteriolar reflex vasospasm (VAR-VAS) is possibly the most frequent pathway. It follows a high-pressure injection of the sclerosant in a target vein resulting in a rapid rise of intravenous pressures which in-turn would trigger a sympathetic neuronal reflex vasospasm of the pre-capillary sphincters and a corresponding opening of the normally closed arterio-venous anastomoses (AVAs). This communication would allow entry of the sclerosing agent into the arteriolar side of the circulation resulting in arteriolar occlusion and infarction of the corresponding skin. Similarly, an intravenous administration of sclerosants in the vicinity of defective boundary valves or persistently open AVAs can result in the entry of detergent agents into the arteriolar side of the microvasculature causing an ischemic stellate ulcer.Conclusions: In this first instalment of these two-part series, we review the pathogenic mechanisms of post-sclerotherapy necrosis. In the second instalment, we describe risk minimisation and management strategies.

Detergent sclerosants at sub-lytic concentrations induce endothelial cell apoptosis through a caspase dependent pathway

To investigate the apoptotic effects of detergent sclerosants sodium tetradecylsulphate (STS) and polidocanol (POL) on endothelial cells at sub-lytic concentrations. Human umbilical vein endothelial cells (HUVECs) were isolated and labelled with antibodies to assess for apoptosis and examined with confocal microscopy and flow cytometry. Isolated HUVECs viability was assessed using propidium iodide staining. Early apoptosis was determined by increased phosphatidylserine exposure by lactadherin binding. Caspase 3, 8, 9 and Bax activation as well as inhibitory assays with Pan Caspase (Z-VAD-FMK) and Bax (BI-6C9) were assessed to identify apoptotic pathways. Porimin activation was used to assess cell membrane permeability. Cell lysis reached almost 100 % with STS at 0.3 % and with POL at 0.6 %. Apoptosis was seen with both STS and POL at concentrations ranging from 0.075 to 0.15 %. PS exposure increased with both STS and POL and exhibited a dose-dependent trend. Active Caspase 3, 8 and 9 but not Bax were increased in HUVECs stimulated with low concentrations of both STS and POL. Inhibitory assays demonstrated Caspase 3, 8, 9 inhibition at low concentrations (0.075 to 0.6 %) with both STS and POL. Both agents increased the activation of porimin at all concentrations. Both sclerosants induced endothelial cell (EC) apoptosis at sub-lytic concentrations through a caspase-dependant pathway. Both agents induced EC oncosis.

Novel developments in foam sclerotherapy: Focus on Varithena® (polidocanol endovenous microfoam) in the management of varicose veins

Scope Varithena® is a recently approved commercially available drug/delivery unit that produces foam using 1% polidocanol for the management of varicose veins. The purpose of this review is to examine the benefits of foam sclerotherapy, features of the ideal foam sclerosant and the strengths and limitations of Varithena® in the context of current foam sclerotherapy practices. Method Electronic databases including PubMed, Medline (Ovid) SP as well as trial registries and product information sheets were searched using the keywords, 'Varithena', 'Varisolve', 'polidocanol endovenous microfoam', 'polidocanol' and/or 'foam sclerotherapy/sclerosant'. Articles published prior to 20 September 2016 were identified. Results Foam sclerosants have effectively replaced liquid agents due to their physiochemical properties resulting in better clinical outcomes. Medical practitioners commonly prepare sclerosant foam at the bedside by agitating liquid sclerosant with a gas such as room air, using techniques as described by Tessari or the double syringe method. Such physician-compounded foams are highly operator dependent producing inconsistent foams of different gas/liquid compositions, bubble size, foam behaviour and varied safety profiles. Varithena® overcomes the variability and inconsistencies of physician-compounded foam. However, Varithena® has limited applications due to its fixed sclerosant type and concentration, cost and lack of worldwide availability. Clinical trials of Varithena® have demonstrated efficacy and safety outcomes equivalent or better than physician-compounded foam but only in comparison to placebo alone. Conclusion Varithena® is a promising step towards the creation of an ideal sclerosant foam. Further assessment in independent randomised controlled clinical trials is required to establish the advantages of Varithena® over and above the current best practice physician-compounded foam.