D-Glucuronic acid and D-N-acetylglucosamine are linked by β-1,3 bonds (blue) to form a disaccharide. Multiple disaccharides are linked by β-1,4 bonds (red) to form hyaluronic acid. Mammalian and microbial hyaluronidases cleave β-1,4 bonds (red), and leech/hookworm hyaluronidases degrade β-1,3 bonds (blue).
Meyer classified hyaluronidases into three categories according to its mechanism of action. First, mammalian hyaluronidases are endo-β-N-acetylhexosaminidases that break down β-1,4 glycosidic linkages to form tetrasaccharides. Second, leech/hookworm hyaluronidases are endo-β-D-glucuronidases that break down β-1,3 glycosidic bonds to form pentasaccharides and hexasaccharides. Finally, microbial hyaluronidases are classified as hyaluronate lyases. Unlike other hyaluronidases, they do not catalyze hydrolysis reactions; instead, they produce unsaturated disaccharides through a β-elimination reaction at β-1,4 glycosidic linkages (Fig. 1) .
Hyaluronidases are enzymes (endoglycosidases) that can depolymerise HA, leading to its degradation3 by hydrolyzing the disaccharides at hexosaminidic β-1through β-4 linkages.4 Hyaluronidase is licensed in the United Kingdom for enhancing permeation of subcutaneous or intramuscular injections, local anaesthetics, and subcutaneous infusions, and to promote resorption of excess fluids and blood.5 There is considerable evidence for the off-label use of hyaluronidase for managing vascular compromise due to inadvertent intravascular injection or external compression,6 over-correction, asymmetry, and lumps and nodules7 caused by the injection of HA filler.
There are several sources of hyaluronidase, and they are generally divided into three subgroups: mammalian (obtained from the testes); hookworm or leech; and microbes.8 Recombinant human hyaluronidase (Hylenex, Halozyme Therapeutics, San Diego, California) has a purity 100 times higher than some of the bovine preparations.9 There is no longterm data for this product yet, but it has been speculated to have a lower incidence of allergic reactions.
Tyndall effect. The Tyndall effect refers to the scattering of light that may be seen in some patients after injection of HA resulting in a bluish hue of the skin and most commonly seen in the sub ocular region. The problem can be resolved using hyaluronidase (Refer to ACE Group guidance on the Tyndall effect20).
Unacceptable cosmetic outcome. Overcorrection or misplacement of HA filler can be successfully treated with hyaluronidase, although this is often caused by poor injection technique or poor choice of product for a particular indication. If HA is present, then hyaluronidase is effective, and HA gel has been successfully removed 63 months post-treatment.21
Delayed onset nodules. Lumps or nodules that appear several months after the initial treatment might be amenable with hyaluronidase (Refer to ACE Group guidance on delayed onset nodules 22). It is important to remember that hyaluronidase is used to help diffuse fluids intradermally and for hypodermoclysis. To prevent potential dissemination of infection in inflammed nodules, it is important to prescribe antibiotics for one week before administering hyaluronidase.
Hyaluronidase may be reconstituted with either saline or water for injection (Hyalase SPC). Saline is less painful on injection and is recommended for this reason. Although unlicensed for this purpose, bacteriostatic saline is often preferred for its additional anaesthetic properties. Although local anaesthetics may be used to reconstitute the product, as the enzymatic action of hyaluronidase can be affected by pH7, caution should be applied to the choice of diluent. There is little evidence to support the addition of local anaesthetic agents to hyaluronidase,18 and when combined, may lead to widespread, increased systemic absorption of anaesthetic and potential complications.
The literature offers examples of widely divergent doses; however, it is recommended to inject as much hyaluronidase as required to obtain the desired effect rather than following an absolute dosage.14
A consensus opinion in the literature states five units of hyaluronidase is needed to break down 0.1mL of 20mg/mL HA,10 although there is quite a range. In one instance, Woodward et al25 recommend 30 units to dissolve 0.1mL. A further study showed no statistical difference between the use of 20 or 40 units of hyaluronidase in degrading 0.2mL (4 to 6mg of HA) of various fillers.23
Nodules, and product that has been injected into the superficial dermis should be injected directly, injections should be placed immediately into and below the product.38[[Not sure what the previous sentence is trying to convey]] For vascular compromise, serial puncture should be used to inject hyaluronidase along the course of the vessel and cover the affected area.4 The needle should be perpendicular to the skin and several injections are often necessary.
Hyalase (hyaluronidase 1500 units) has an off-license use in aesthetic medicine and except in the case of emergency administration requires the patient to undergo a skin patch test at least twenty minutes prior to the procedure being undertaken. The skin patch test is carried out by injecting Hyalase into the subcutaneous tissue of the forearm and observed for signs of reaction (i.e. hives or wheals). If a positive patch test result is observed, treatment with Hyalase cannot be carried out. Erythema or redness and slight vasodilation may be expected.
Hyalase is an enzyme which breaks down hyaluronic acid fillers, but it can also break down naturally occurring hyaluronic acid present in the body, the results can be unpredictable and the effect dramatic. I understand that there will be loss of volume and there can be some skin laxity which in itself may not provide a good aesthetic result. Although some of the effects can be immediate, I understand that it can take up to 14 days for the final results to be seen and the treatment may need to be repeated.
Hyalase is an enzyme which breaks down hyaluronic acid fillers, but it can also break down naturally occurring hyaluronic acid present in the body. The results can be unpredictable and the effect dramatic with possible loss of volume and some skin laxity. Although some of the effects can be immediate, it can take up to 2 weeks for the final results to be seen and the procedure may need to be repeated.
Hyaluronidase from honey bee was recombinantly expressed as a secreted glycoprotein in Pichia pastoris. The active enzyme was produced in milligram quantities per liter of primary culture. When changing the codons of the original transcript to triplet sequences preferred by P. pastoris, no further increase of protein product could be achieved. After expression of a fusion protein by linking hyaluronidase and human serum albumin together with the recognition sequence for the protease, factorXa, fragmented protein products were obtained in the culture supernatant. Only after replacement of the hinge region with a serine-glycine-rich linker, stable full-length fusion protein could be generated. The protein products were purified by cation exchange chromatography at pH 5.0 and pure enzyme fractions were further characterized in detail. The biochemical properties of the product matched those of crude hyaluronidase within bee venom: the native and the recombinant enzyme exhibited activity over a pH range from 3 to 8 (maximum: 3.8), at temperatures as low as 4 degrees C and up to 90 degrees C (maximum 62 degrees C), and at ionic strength as high as 2 M salt. Recombinant bee hyaluronidase efficiently degrades 6-S-chondroitin sulfate (chondroitin sulfate C) as well as 4-S-chondroitin sulfate (chondroitin sulfate A), the latter to a lesser extent. Only very little hydrolase activity towards chondroitin sulfate B (dermatan sulfate) was detectable.
Purpose: Evaluate the codelivery of hyaluronidase enzyme with oncolytic adenoviruses to determine whether it improves the spread of the virus throughout tumors, thereby leading to a greater overall antitumor efficacy in tumor models.
Experimental design: The optimal dose of hyaluronidase that provided best transduction efficiency and spread of a green fluorescent protein (GFP)-expressing adenovirus within tumors was combined with oncolytic viruses in tumor models to determine whether the combination treatment results in an improvement of antitumor efficacy.
Results: In mice injected with the adenovirus Ad5/35GFP and an optimal dose of hyaluronidase (50 U), a significant increase in the number of GFP-expressing cells was observed when compared with animals injected with virus only (P < 0.0001). When the oncolytic adenoviruses Ad5OV or Ad5/35 OV (OV-5 or OV5T35H) were codelivered with 50 U of hyaluronidase, a significant delay in tumor progression was observed, which translated into a significant increase in the mean survival time of tumor-bearing mice compared with either of the monotherapy-treated groups (P < 0.0001). Furthermore, the mice that received the combination of Ad5/35 OV and hyaluronidase showed the best antitumor efficacy. Importantly, the combination treatment did not increase the metastatic potential of the tumors. Lastly, the increase in virus potency observed in animals injected with both enzyme and virus correlated with enhanced virus spread throughout tumors.
Conclusion: Antitumor activity and overall survival of mice bearing highly aggressive tumors are significantly improved by codelivery of oncolytic adenoviruses and hyaluronidase when compared with either of the monotherapy-treated groups, and it may prove to be a potent and novel approach to treating patients with cancer.
Hyaluronidase is an enzyme (compounded by special pharmacies) that causes hydrolysis (breakdown) of hyaluronic acid. It is often referred to as a reversal agent for hyaluronic acid fillers. When the enzyme is injected it dissolves the synthetic hyaluronic acid filler, leaving your own intac