Prospective bacterial and fungal sources of hyaluronic acid: A review

Microbial production of hyaluronic acid: The current advances, engineering strategies and trends

Hyaluronic acid (HA) is a versatile biomolecule with applications in medicine, cosmetics, and pharmaceuticals. While traditionally extracted from animal tissues, HA is now predominantly produced through microbial fermentation. Microbial fermentation using strains such as Streptococcus zooepidemicus, Corynebacterium glutamicum, and Bacillus subtilis offers a more scalable and sustainable alternative to chemical and animal extraction methods. Recent studies reveal promising yields from engineered strains of Corynebacterium glutamicum and Bacillus subtilis, utilizing advanced metabolic and genetic techniques. Recent advancements in genetic and metabolic engineering, as well as synthetic biology, have addressed some challenges related to molecular weight, viscosity, and by-product formation. This review focuses on the microbial production of HA using engineered strains, encompassing producer organisms, metabolic engineering strategies, industrial-scale production, and key factors influencing molecular weight. Furthermore, it addresses the challenges and potential solutions associated with HA production. Additional research is necessary to develop more efficient and robust engineered strains that exhibit resistance to contamination and can utilize low-cost substrates, such as Pseudomonas putida and Halomonas spp. By overcoming these challenges, researchers can advance the industrial production of HA and expand its applications, thereby contributing to the growth of the HA market.

CRISPRi-assisted metabolic engineering of cyanobacteria for photosynthetic hyaluronic acid from CO2

BACKGROUND

Hyaluronic acid (HA) is widely used in pharmaceuticals, medicine, and cosmetics. Sustainable production has shifted to microbial fermentation using engineered GRAS strains. Diverse carbon sources and CO2 conversion via engineered microorganisms enhance HA production. Herein we applied advances in CRISPR technologies and tools to optimize metabolic pathway by redirecting carbon portioning in cyanobacterium Synechoccous elongatus PCC 7942, demonstrating enhanced HA production.

RESULTS

S. elongatus PCC 7942 lacking hyaluronan synthase (HAS) required pathway engineering for HA production. By expressing heterologous Class I HAS, a modular gene expression system was employed, incorporating hasB and hasC for the HA-GlcA module and glmU, glmM, and glmS for the GlcNAc module. This approach resulted in construction of four engineered cyanobacterial strains. Optimizing metabolic pathway involving the HA-GlcA and GlcNAc modules led to SeHA220 (wild-type with HA-GlcA and GlcNAc modules) producing 2.4 ± 0.85 mg/L HA at 21 d, a 27.5-fold increase compared to the control. Targeting F6P and G6P metabolic nodes via CRISPR interference to repress zwf and pfk genes further improved production, with SeHA226 (SeHA220 with a gene repression module) achieving 5.0 ± 0.3 mg/L HA from CO2 at 15 d. Notably, SeHA226 produced photosynthetic HA with a molecular weight (Mw) of 4.2 MDa, comparable to native producers, emphasizing the importance of precursor balance and growth conditions.

CONCLUSIONS

This study engineered cyanobacteria for efficient HA biosynthesis using modular gene expression and CRISPR-interference systems. Optimizing heterologous metabolic pathway was key to achieving high-molecular-weight photosynthetic HA production from CO2. The findings provide insights into tunable HA production, with future efforts aimed at scaling up photosynthetic HA production for larger-scale applications.

Metabolic engineering of Escherichia coli for enhanced production of hyaluronic acid

OBJECTIVES

To enhance hyaluronic acid (HA) production in Escherichia coli by utilizing hasA genes from Streptococcus pyogenes and Streptococcus parauberis, and employing metabolic engineering strategies.

RESULTS

The expression of the hasA (SpaHasA) gene from S. parauberis in E. coli K12 W3110 led to higher HA production compared to the other gene. Knockout of the zwf and pfkA genes in the engineered E. coli expressing SpaHasA gene, further increased HA production to 891 mg l-1. Overexpression of the galU and ugd genes in the zwf and pfkA double mutant harboring the SpaHasA gene elevated HA output to 1017 mg l-1. Using the same engineered E. coli strain, optimizing the MgSO4 concentration in the culture medium enhanced production to 1187 mg l-1, and in fed-batch fermentation, it achieved 2283 mg HA l-1.

CONCLUSIONS

The hasA genes from various Streptococcus groups, especially S. parauberis, significantly boost HA production in E. coli, demonstrating their potential for microbial fermentation applications.

Microbes, macrophages, and melanin: a unifying theory of disease as exemplified by cancer

It is widely accepted that cancer mostly arises from random spontaneous mutations triggered by environmental factors. Our theory challenges the idea of the random somatic mutation theory (SMT). The SMT does not fit well with Charles Darwin's theory of evolution in that the same relatively few mutations would occur so frequently and that these mutations would lead to death rather than survival of the fittest. However, it would fit well under the theory of evolution, if we were to look at it from the vantage point of pathogens and their supporting microbial communities colonizing humans and mutating host cells for their own benefit, as it does give them an evolutionary advantage and they are capable of selecting genes to mutate and of inserting their own DNA or RNA into hosts. In this article, we provide evidence that tumors are actually complex microbial communities composed of various microorganisms living within biofilms encapsulated by a hard matrix; that these microorganisms are what cause the genetic mutations seen in cancer and control angiogenesis; that these pathogens spread by hiding in tumor cells and M2 or M2-like macrophages and other phagocytic immune cells and traveling inside them to distant sites camouflaged by platelets, which they also reprogram, and prepare the distant site for metastasis; that risk factors for cancer are sources of energy that pathogens are able to utilize; and that, in accordance with our previous unifying theory of disease, pathogens utilize melanin for energy for building and sustaining tumors and metastasis. We propose a paradigm shift in our understanding of what cancer is, and, thereby, a different trajectory for avenues of treatment and prevention.

Hyaluronic Acid is Associated with Severity and Prognosis in Patients with Community-Acquired Pneumonia

Purpose

Hyaluronic acid (HA) is a novel inflammatory biomarker with a prognostic value for several infectious diseases. This study investigated the association of HA with severity and prognosis in hospitalized patients with community-acquired pneumonia (CAP).

Patients and Methods

We analyzed the differences of HA levels in different groups. Logistic regression analysis was performed to identify independent risk factors for severe CAP (SCAP). The predictive value of HA for SCAP was assessed using receiver operating characteristic (ROC) curves. Kaplan-Meier survival analysis was used to compare 30-day mortality between the high and low HA groups.

Results

Compared to healthy controls (49.2 ± 15.3 ng/mL), patients with CAP exhibited significantly elevated levels of HA (P < 0.001). In CAP patients, increased HA levels were more pronounced in those with SCAP (SCAP vs non-SCAP:135.6 ± 51 ng/mL vs 100.7 ± 47.8 ng/mL, P < 0.001). Compared to survivors (109.9 ± 48.7 ng/mL), HA levels in non-survivors were significantly higher (180.9 ± 67.8 ng/mL) (P < 0.001). HA was an independent predictor of SCAP [odds ratio (OR): 1.013, 95% confidence interval (CI): 1.003-1.022, P = 0.011] with high diagnostic accuracy [areas under the curve (AUC): 0.709, 95% CI: 0.622-0.797, P = 0.001]. Additionally, HA was independently associated with death risk in patients with CAP (OR: 1.022, 95% CI: 1.005-1.039, P = 0.010). Kaplan-Meier survival curves indicated that CAP patients in the high HA group exhibit a higher 30-day mortality rate compared to those in the low HA group (8.6% vs 1.5%, P = 0.008). Post hoc analysis indicated that our study possessed 98.857% statistical power.

Conclusion

In conclusion, High HA levels are associated with severity and mortality in patients with CAP, and HA could serve as a novel serum biomarker to predict the risk of CAP progression.

Comparative analysis of in vivo bio-integration of three hyaluronic acid-based fillers for 26 weeks: a histological study

Stabilized hyaluronic acid (HA), produced through diverse cross-linking technology and formulated as an injectable gel, has found widespread utilization in aesthetic industry. Cross-linked HA essentially constitutes a gel particle composition formed by numerous viscoelastic particulates. Various product formulations yield HA gels with distinct properties, including particle size, viscoelasticity, and interaction forces between particles. While previous studies have primarily concentrated on the biological safety and macroscopic expression of fillers, limited research exists on the internal mechanisms governing their macro-performance. This study selected three common dermal fillers for analysis, establishing an animal model to assess their in vivo interaction with surrounding tissues and explore their internal mechanisms. The findings revealed that particle size plays a crucial role in tissue integration.

Effect of hyaluronic acid-stabilized silver nanoparticles on lettuce (Lactuca sativa L.) seed germination

Nanotechnology has brought significant advancements to agriculture through the development of engineered nanomaterials (ENPs). Silver nanoparticles (AgNPs) capped with polysaccharides have been applied in agricultural diagnostics, crop pest management, and seed priming. Hyaluronic acid (HA), a natural polysaccharide with bactericidal properties, has been considered a growth regulator for plant tissues and an inducer of systemic resistance against plant diseases. Additionally, HA has been employed as a stabilizing agent for AgNPs. This study investigated the synthesis and effects of hyaluronic acid-stabilized silver nanoparticles (HA-AgNPs) as a seed priming agent on lettuce (Lactuca sativa L.) seed germination. HA-AgNPs were characterized using several techniques, exhibiting spherical morphology and good colloidal stability. Germination assays conducted with 0.1, 0.04, and 0.02 g/L of HA-AgNPs showed a concentration-dependent reduction in seed germination. Conversely, lower concentrations of HA-AgNPs significantly increased germination rates, survival, tolerance indices, and seed water absorption compared to silver ions (Ag+). SEM/EDS indicated more significant potential for HA-AgNPs internalization compared to Ag+. Therefore, these findings are innovative and open new avenues for understanding the impact of Ag+ and HA-AgNPs on seed germination.

ViSCNOVAS: A Novel Classification System for Hyaluronic Acid-Based Gels in Orthobiologic Products and Regenerative Medicine

Hyaluronic acid (HA), a naturally occurring polysaccharide, holds immense potential in regenerative medicine due to its diverse biological functions and clinical applications, particularly in gel formulations. This paper presents a comprehensive exploration of HA, encompassing its origins, molecular characteristics, and therapeutic roles in gel-based interventions. Initially identified in bovine vitreous humor, HA has since been found in various tissues and fluids across vertebrate organisms and bacterial sources, exhibiting consistent physicochemical properties. The synthesis of HA by diverse cell types underscores its integral role in the extracellular matrix and its relevance to tissue homeostasis and repair. Clinical applications of HA, particularly in addressing musculoskeletal ailments such as osteoarthritis, are examined, highlighting its efficacy and safety in promoting tissue regeneration and pain relief. Building upon this foundation, a novel classification system for HA-based interventions is proposed, aiming to standardize treatment protocols and optimize patient outcomes. The ViSCNOVAS classification system refers to viscosity, storage, chain, number, origin, volume, amount, and size. This classification is specifically designed for HA-based orthobiologic products used in regenerative medicine, including orthopedics, sports medicine, aesthetics, cosmetic dermatology, and wound healing. It aims to provide clinicians with a structured framework for personalized treatment strategies. Future directions in HA research are also discussed, emphasizing the need for further validation and refinement of the proposed classification system to advance the field of regenerative medicine. Overall, this manuscript elucidates the biological functions of hyaluronic acid and its potential in clinical practice while advocating for standardization to enhance patient care in various regenerative applications.

Advances in Polysaccharides for Cartilage Tissue Engineering Repair: A Review

Cartilage repair has been a significant challenge in orthopedics that has not yet been fully resolved. Due to the absence of blood vessels and the almost cell-free nature of mature cartilage tissue, the limited ability to repair cartilage has resulted in significant socioeconomic pressures. Polysaccharide materials have recently been widely used for cartilage tissue repair due to their excellent cell loading, biocompatibility, and chemical modifiability. They also provide a suitable microenvironment for cartilage repair and regeneration. In this Review, we summarize the techniques used clinically for cartilage repair, focusing on polysaccharides, polysaccharides for cartilage repair, and the differences between these and other materials. In addition, we summarize the techniques of tissue engineering strategies for cartilage repair and provide an outlook on developing next-generation cartilage repair and regeneration materials from polysaccharides. This Review will provide theoretical guidance for developing polysaccharide-based cartilage repair and regeneration materials with clinical applications for cartilage tissue repair and regeneration.

Bacterial capsules: Occurrence, mechanism, and function

In environments characterized by extended multi-stress conditions, pathogens develop a variety of immune escape mechanisms to enhance their ability to infect the host. The capsules, polymers that bacteria secrete near their cell wall, participates in numerous bacterial life processes and plays a crucial role in resisting host immune attacks and adapting to their niche. Here, we discuss the relationship between capsules and bacterial virulence, summarizing the molecular mechanisms of capsular regulation and pathogenesis to provide new insights into the research on the pathogenesis of pathogenic bacteria.

In vitro Cytotoxicity Evaluation of Flowable Hyaluronic Acid-Acellular Stromal Vascular Fraction (HA-aSVF) Mixture for Tissue Engineering Applications

Background

The stromal vascular fraction (SVF) is an aqueous fraction isolated from the adipose tissue that constitutes different kinds of cells and extracellular matrix components. Hyaluronic acid (HA) is a linear polysaccharide in vertebrate tissues and is considered a potential tissue engineering scaffold due to its biocompatible nature. In this study, we have evaluated the cytotoxicity of xenofree HA in combination with an acellular component of adipose SVF (HA-aSVF) to propose it as a candidate biomaterial for future applications.

Materials and Methods

3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyltetrazolium bromide assay of L-929 cells treated with HA-aSVF was used in our study. Data were normalized to cell control (untreated) and extracts of copper and ultra-high molecular weight polyethylene were used as positive (PC) and negative controls (NC).

Results

Fibroblast cells retained the morphology after 24 h of treatment with HA-aSVF mixture and exhibited a similar percentage of cell activity compared to NC. PC showed a positive cytotoxic response as expected. The cells incubated with HA-aSVF showed a linear increase in cell activity indicating proliferation.

Conclusion

The mixture of HA and acellular SVF in its flowable form is non-cytotoxic and showed improved cell proliferation. Hence the mixture can be proposed as a biomaterial and can be further explored for specific tissue engineering applications.