Quantification of hyaluronan (HA) using a simplified fluorophore-assisted carbohydrate electrophoresis (FACE) procedure

Characterization of the Molecular Weight of Hyaluronan in Eye Products Using a Novel Method of Size Exclusion High-Pressure Liquid Chromatography

Purpose

Hyaluronan (HA) exists in two forms, high molecular weight HA (HMWHA) and low molecular weight HA (LMWHA), which have distinct physiological functions. Therefore it is imperative to know the form of HA within pharmaceutical products, including eye products. This study developed an accurate, sensitive, and quantitative method to characterize the form of HA in eye products. Thereafter, the effects of the HA-containing eye products on corneal wound healing were investigated.

Methods

The MW distributions and concentrations of HA in over the counter eye products were determined by size exclusion chromatography (SEC) high-pressure liquid chromatography (HPLC). The effects of the eye products containing HA on corneal wound healing were characterized both in vitro and in vivo using the scratch assay and the debridement wound model, respectively.

Results

The concentrations and MWs of HA were successfully determined within a range of 0.014 to 0.25 mg/mL using SEC HPLC. The concentrations of HA in the ophthalmic products varied from 0.14 to 4.0 mg/mL and the MWs varied from ∼100 kDa to >2500 kDa. All but one HA-containing eye product had an inhibitory effect on corneal wound healing, whereas pure HA promoted corneal wound healing.

Conclusions

A novel SEC-HPLC method was developed for quantifying and characterizing the MW of HA in eye products. Although HA promoted corneal wound healing, HA-containing eye products inhibited corneal wound healing, likely caused by preservatives.

Translational Relevance

SEC-HPLC could be implemented as a routine method for determining the form of HA in commercially available ophthalmic products.

Isolation and Compositional Analysis of Glycosaminoglycans

The compositional and structural analysis of GAGs is challenging due to their heterogenous structures. Strong anion exchange (SAX) HPLC can aid in the compositional analysis of GAGs and can separate complex mixtures based on charge and degree of sulfation. Herein we describe the digestion and release of GAGs from tissue, and the compositional analysis using SAX-HPLC.

Nutrient niche specificity for glycosaminoglycans is reflected in polysaccharide utilization locus architecture of gut Bacteroides species

INTRODUCTION

Glycosaminoglycans (GAGs) present in the mucosal layer can be used as nutrients by certain intestinal bacteria, particularly members of the Bacteroides. GAG abundances are altered in some diseases such as inflammatory bowel diseases, which may affect microbial composition and activity, and it is therefore important to understand GAG utilization by members of the gut microbiota.

METHODS

We used growth assays, transcriptomics, and comparative genomics to evaluate chondroitin sulfate (CS) and hyaluronan (HA) degradation ability by multiple gut Bacteroides species.

RESULTS AND DISCUSSION

We found that not all Bacteroides species able to degrade CS could also degrade HA, despite having lyases which act on both compounds. We propose that in the model organism Bacteroides thetaiotaomicron, the lyase BT_3328 in combination with surface binding proteins BT_3329 and BT_3330 and potentially BT_4411 are involved in HA breakdown. Furthermore, degradation of both compounds provides public goods for other Bacteroides, including non-degraders, suggesting that cooperative degradation as well as cross-feeding may be widespread in the mucosal glycan utilization clade.

The versican-hyaluronan complex provides an essential extracellular matrix niche for Flk1+ hematoendothelial progenitors

Little is known about extracellular matrix (ECM) contributions to formation of the earliest cell lineages in the embryo. Here, we show that the proteoglycan versican and glycosaminoglycan hyaluronan are associated with emerging Flk1⁺ hematoendothelial progenitors at gastrulation. The mouse versican mutant Vcan^hdf lacks yolk sac vasculature, with attenuated yolk sac hematopoiesis. CRISPR/Cas9-mediated Vcan inactivation in mouse embryonic stem cells reduced vascular endothelial and hematopoietic differentiation within embryoid bodies, which generated fewer blood colonies, and had an impaired angiogenic response to VEGF₁₆₅. Hyaluronan was severely depleted in Vcan^hdf embryos, with corresponding upregulation of the hyaluronan-depolymerase TMEM2. Conversely, hyaluronan-deficient mouse embryos also had vasculogenic suppression but with increased versican proteolysis. VEGF₁₆₅ and Indian hedgehog, crucial vasculogenic factors, utilized the versican-hyaluronan matrix, specifically versican chondroitin sulfate chains, for binding. Versican-hyaluronan ECM is thus an obligate requirement for vasculogenesis and primitive hematopoiesis, providing a vasculogenic factor-enriching microniche for Flk1⁺ progenitors from their origin at gastrulation.

Cardiac mesenchymal cells from failing and nonfailing hearts limit ventricular dilation when administered late after infarction

Although cell therapy-mediated cardiac repair offers promise for treatment/management of heart failure, lack of fundamental understanding of how cell therapy works limits its translational potential. In particular, whether reparative cells from failing hearts differ from cells derived from nonfailing hearts remains unexplored. Here, we assessed differences between cardiac mesenchymal cells (CMC) derived from failing (HF) versus nonfailing (Sham) hearts and whether the source of donor cells (i.e., from HF vs. Sham) limits reparative capacity, particularly when administered late after infarction. To determine the impact of the donor source of CMCs, we characterized the transcriptional profile of CMCs isolated from sham (Sham-CMC) and failing (HF-CMC) hearts. RNA-seq analysis revealed unique transcriptional signatures in Sham-CMC and HF-CMC, suggesting that the donor source impacts CMC. To determine whether the donor source affects reparative potential, C57BL6/J female mice were subjected to 60 min of regional myocardial ischemia and then reperfused for 35 days. In a randomized, controlled, and blinded fashion, vehicle, HF-CMC, or Sham-CMC were injected into the lumen of the left ventricle at 35 days post-MI. An additional 5 weeks later, cardiac function was assessed by echocardiography, which indicated that delayed administration of Sham-CMC and HF-CMC attenuated ventricular dilation. We also determined whether Sham-CMC and HF-CMC treatments affected ventricular histopathology. Our data indicate that the donor source (nonfailing vs. failing hearts) affects certain aspects of CMC, and these insights may have implications for future studies. Our data indicate that delayed administration of CMC limits ventricular dilation and that the source of CMC may influence their reparative actions.NEW & NOTEWORTHY Most preclinical studies have used only cells from healthy, nonfailing hearts. Whether donor condition (i.e., heart failure) impacts cells used for cell therapy is not known. We directly tested whether donor condition impacted the reparative effects of cardiac mesenchymal cells in a chronic model of myocardial infarction. Although cells from failing hearts differed in multiple aspects, they retained the potential to limit ventricular remodeling.

Functional maturation of human neural stem cells in a 3D bioengineered brain model enriched with fetal brain-derived matrix

Brain extracellular matrix (ECM) is often overlooked in vitro brain tissue models, despite its instructive roles during development. Using developmental stage-sourced brain ECM in reproducible 3D bioengineered culture systems, we demonstrate enhanced functional differentiation of human induced neural stem cells (hiNSCs) into healthy neurons and astrocytes. Particularly, fetal brain tissue-derived ECM supported long-term maintenance of differentiated neurons, demonstrated by morphology, gene expression and secretome profiling. Astrocytes were evident within the second month of differentiation, and reactive astrogliosis was inhibited in brain ECM-enriched cultures when compared to unsupplemented cultures. Functional maturation of the differentiated hiNSCs within fetal ECM-enriched cultures was confirmed by calcium signaling and spectral/cluster analysis. Additionally, the study identified native biochemical cues in decellularized ECM with notable comparisons between fetal and adult brain-derived ECMs. The development of novel brain-specific biomaterials for generating mature in vitro brain models provides an important path forward for interrogation of neuron-glia interactions.

Degradation of tumour stromal hyaluronan by small extracellular vesicle-PH20 stimulates CD103+ dendritic cells and in combination with PD-L1 blockade boosts anti-tumour immunity

Highly accumulated hyaluronan (HA) not only provides a physiological barrier but also supports an immune-suppressive tumour microenvironment. High-molecular-weight (HMW)-HA inhibits the activation of immune cells and their access into tumour tissues, whereas, low-molecular-weight oligo-HA is known to potentially activate dendritic cells (DCs). In this paper, we investigated whether small extracellular vesicle (EVs)-PH20 hyaluronidase induces tumour HA degradation, which, in turn, activates DCs to promote anti-cancer immune responses. Informed by our previous work, we used a small EV carrying GPI-anchored PH20 hyaluronidase (Exo-PH20) that could deeply penetrate into tumour foci via HA degradation. We found that Exo-PH20-treatment successfully activates the maturation and migration of DCs in vivo, particularly CD103⁺ DCs leading to the activation of tumour-specific CD8⁺ T cells, which work together to inhibit tumour growth. Moreover, combination with anti-PD-L1 antibody provided potent tumour-specific CD8⁺ T cell immune responses as well as elicited prominent tumour growth inhibition both in syngenic and spontaneous breast cancer models, and this anti-tumour immunity was durable. Together, these results present new insights for HA degradation by Exo-PH20, providing a better understanding of oligo HA-triggered immune responses to cancer.

A guide to hyaluronan and related enzymes in breast cancer: biological significance and diagnostic value

Hyaluronan (HA) is a unique nonsulfated glycosaminoglycan that contributes to breast cancer cells growth and functional properties, including cell migration, invasion, adhesion, as well as tumor-associated angiogenesis in different stages of breast cancer progression and especially metastasis. Latest data show that the levels of HA and/or low molecular mass HA in blood serum and plasma of breast cancer patients may be a useful biomarker for breast cancer prognosis, differential diagnosis, and patients' treatment monitoring. Therefore, the qualitative and quantitative determination of HA in biological samples is an emerging area of research. This review gathers, categorizes, and sums up all the currently used methodologies to analyze HA and HA-related enzymes. The advantages, disadvantages, limitations in use, and the information they provide, are critically considered and discussed. Moreover, emphasis is given to the significance of HA determination in breast cancer, as well as of its related enzymes, for diagnosis and prognosis of this type of cancer.

Cardiac fibroblast activation and hyaluronan synthesis in response to hyperglycemia and diet-induced insulin resistance

Diabetic patients are at a greater risk of heart failure due to diabetic cardiomyopathy and worsened outcome post-myocardial infarction. While the molecular mechanisms remain unclear, fibrosis and chronic inflammation are common characteristics of both conditions. Diabetes mellitus (types I and II) results in excessive hyaluronan (HA) deposition in vivo, and hyperglycemia stimulates HA synthesis for several cell types in vitro. HA-rich extracellular matrix contributes to fibrotic, hyperplastic and inflammatory disease progression. We hypothesized that excessive hyperglycemia-driven HA accumulation may contribute to pathological fibroblast activation and fibrotic remodelling in diabetic patients. Therefore, we analysed the impact of both hyperglycemia and diet-induced obesity and insulin resistance on HA matrix formation and cardiac fibroblast activation. Here we report that cardiac fibroblasts isolated from mice on a diabetogenic diet acquire pro-fibrotic gene expression without a concomitant increase in HA matrix deposition. Additionally, hyperglycemia alone does not stimulate HA synthesis or cardiac fibroblast activation in vitro, suggesting that the direct effect of hyperglycemia on fibroblasts is not the primary driver of fibrotic remodelling in cardiac diabetic maladaptation.