Thangavelu Muthukumar

Background: Bacterial keratitis, a major cause of corneal blindness, is frequently associated with biofilm-forming pathogens such as Klebsiella pneumoniae. Cyclic-di-GMP (c-di-GMP) controls biofilm development, which increases antibiotic resistance and makes treatment more difficult, highlighting the need for innovative therapeutic approaches. Methods: This study investigated cinnamaldehyde as a potential ocular therapeutic using combined computational and experimental approaches. Molecular docking and in vitro assays (XTT, resazurin reduction, crystal violet staining, qRT-PCR, and fluorescence microscopy) were used to evaluate the anti-biofilm and immunomodulatory activities of cinnamaldehyde (CA) against Klebsiella pneumoniae. Results: CA inhibited biofilm formation in a dose-dependent manner (≈89% at 1000 µM; >50% at 250 µM), reduced bacterial attachment to contact lenses, and downregulated key biofilm genes (mrkA, mrkC, ybtS, bolA). Docking analysis revealed strong binding affinity to the mrkH regulator (−5.46 kcal/mol. CA maintained more than 80% corneal cell viability by increasing IL-10, suppressing inflammatory mediators (IL-1β, IL-6, and TNF-α), and improving bacterial clearance. Conclusions: This study combines computational docking, biofilm quantification, immune cell assays, and functional gene expression analyses to reveal the ability of cinnamaldehyde not only to suppress biofilm formation but also to enhance macrophage-mediated clearance and modulate corneal immune responses, a multi-target approach not previously described in the context of bacterial keratitis. Such effects highlight its potential as a novel ocular drug candidate for protecting corneal integrity in infectious keratitis.

Engineered bone scaffolds should mimic the natural material to promote cell adhesion and regeneration. For this reason, natural biopolymers are becoming a gold standard in scaffold production. In this study, we proposed a hybrid scaffold produced using gellan gum, hydroxyapatite, and Poly (ethylene glycol) within the addition of the ginseng compound K (CK) as a candidate for bone regeneration. The fabricated scaffold was physiochemically characterized. The morphology studied by scanning electron microscopy (SEM) and image analysis revealed a pore distribution suitable for cells growth. The addition of CK further improved the biological activity of the hybrid scaffold as demonstrated by the MTT assay. The addition of CK influenced the scaffold morphology, decreasing the mean pore diameter. These findings can potentially help the development of a new generation of hybrid scaffolds to best mimic the natural tissue.

Progressive aging harms bone tissue structure and function and, thus, requires effective therapies focusing on permanent tissue regeneration rather than partial cure, beginning with regenerative medicine. Due to advances in tissue engineering, stimulating osteogenesis with biomimetic nanoparticles to create a regenerative niche has gained attention for its efficacy and cost-effectiveness. In particular, hydroxyapatite (HAP, Ca₁₀(PO₄)₆(OH)₂) has gained significant interest in orthopedic applications as a major inorganic mineral of native bone. Recently, magnetic nanoparticles (MNPs) have also been noted for their multifunctional potential for hyperthermia, MRI contrast agents, drug delivery, and mechanosensitive receptor manipulation to induce cell differentiation, etc. Thus, the present study synthesizes HAP-decorated MNPs (MHAP NPs) via the wet chemical co-precipitation method. Synthesized MHAP NPs were evaluated against the preosteoblast MC3T3-E1 cells towards concentration-dependent cytotoxicity, proliferation, morphology staining, ROS generation, and osteogenic differentiation. The result evidenced that MHAP NPs concentration up to 10 µg/mL was non-toxic even with the time-dependent proliferation studies. As nanoparticle concentration increased, FACS apoptosis assay and ROS data showed a significant rise in apoptosis and ROS generation. The MC3T3-E1 cells cocultured with 5 µg/mL MHAP NPs showed significant osteogenic differentiation potential. Thus, MHAP NPs synthesized with simple wet chemistry could be employed in bone regenerative therapy.

In this study, collagen hydrolysates (CHDs) were fabricated with honey-propolis wax (HPW), structurally modified as a sponge matrix, and experimentalized on wound healing in a mouse model. The scaffold was characterized by means of in vitro enzymatic degradation; in vitro HPW release; and in vivo wound-healing mouse model, wound-healing-specific RNA, transcripts, and protein markers. The functional activity of the HPW extracted from raw propolis was determined using total flavonoids, antioxidant scavenging assays, and anti-hemolytic principles. The results indicated that HPW had a high flavonoid content (20 μg/mL of wax) and antioxidant activities. The effective concentration (EC50) of HPW was estimated (28 mg/mL) and was then used in the subsequent in vivo experiments. Additionally, the dopped mixture of CHDs and HPW substantially enhanced the wound-healing process and regulated wound biochemical markers such as hexoseamine and melondialdehyde. CHDs- HPW upregulated the expression of growth factors including vascular endothelial growth factor (VEGF) (2.3-fold), fibroblast growth factor (FGF) and epidermal growth factor (EGF) (1.7-fold), and transforming growth factor-beta (TGF-β) (3.1-fold), indicating their potential capacity to perform wound re-epithelialization and the loading of ground tissue. Pro-inflammatory markers IL-1 β (51 pg/mL) and TNF-α (220 pg/mL) were significantly reduced in the CHD-HPW-treated wound. These interesting results were further confirmed using mRNA and protein growth factors from the wound, which enhanced the load of collagen-I in the wound site. In conclusion, CHDs-HPW exhibited a significant reduction in inflammation and inflammatory markers and helped to obtain a faster wound-healing process in a mouse model. The newly engineered biosponge could be developed as a promising therapeutic approach for the regeneration and repair of damaged human skin in the future.

Visual impairment from corneal stromal disease affects millions worldwide. We describe a cell-free engineered corneal tissue, bioengineered porcine construct, double crosslinked (BPCDX) and a minimally invasive surgical method for its implantation. In a pilot feasibility study in India and Iran (clinicaltrials.gov no.NCT04653922), we implanted BPCDX in 20 advanced keratoconus subjects to reshape the native corneal stroma without removing existing tissue or using sutures. During 24 months of follow-up, no adverse event was observed. We document improvements in corneal thickness (mean increase of 209 ± 18 µm in India, 285 ± 99 µm in Iran), maximum keratometry (mean decrease of 13.9 ± 7.9 D in India and 11.2 ± 8.9 D in Iran) and visual acuity (to a mean contact-lens-corrected acuity of 20/26 in India and spectacle-corrected acuity of 20/58 in Iran). Fourteen of 14 initially blind subjects had a final mean best-corrected vision (spectacle or contact lens) of 20/36 and restored tolerance to contact lens wear. This work demonstrates restoration of vision using an approach that is potentially equally effective, safer, simpler and more broadly available than donor cornea transplantation.

Retinal pigment epithelium (RPE) plays a decisive role in the normal function of the retina, especially in the maintenance of photoreceptors. RPE dysfunction, loss of sight, and degeneration has been implicated as the cause of many retinal diseases including pigmented retinitis and age-related macular degeneration (AMD). Silk fibroin (SF) is a biodegradable natural polymer with biocompatibility, non-toxic, and non-immunological properties. In this study, hydrogel material was prepared by mixing it with PEG [poly (ethylene glycol)] a synthetic polymer. SF hydrogel (SH) and with PEG (SPH) were prepared with different sonication times. The SH and SPH were prepared with different sonication time (20s SH, 30s SH, 20s SPH, and 30s SPH were prepared, respectively. The prepared SH and SPH were physio chemically characterized by SEM, FTIR, compressive strength, porosity, and in vitro biocompatibility were analyzed using MTT assay along with cell adhesion and cell proliferation, their gene expression was analyzed using RT-PCR. As a result, the 20s SPH hydrogel exhibited superior biocompatibility, cell adhesion, and improved cell growth compared to pure SH. Their respective genes expression for retinal function and matrix production was also positively influenced by 20s SPH with an increase in gene expression folds of RPE65, CRALBP. The obtained results suggest that the 20s SPH hydrogel can be used as an alternative material for the application of retinal regeneration and delivery.

Biomaterials designed to replace the diseased cornea could be used to treat corneal blindness where human donor tissue is in short supply, but challenges are the integration of biomaterials with host tissue and cells, avoiding a rapid material degradation and maintaining corneal transparency. Additionally, implantation surgery often triggers an aggressive wound healing response that can lead to corneal thinning and opacity. Here, we report a collagen-based hydrogel with transparency and mechanical properties suitable for replacing a substantial portion of a damaged or diseased corneal stroma. The porous hydrogel permitted migration and population by host cells while maintaining transparency and thickness six months after surgical implantation in an in vivo model of human corneal surgery. With a novel hybrid surgical implantation technique inspired by LASIK refractive surgery, rapid wound healing occurred around implants to maintain biomaterial integrity, transparency and function. Host stromal cell repopulation and regeneration of host epithelium and nerves were observed, as necessary steps towards corneal regeneration. Finally, as a proof-of-principle, the hydrogel loaded with a neuroregenerative drug achieved sustained slow-release drug delivery in vitro. The proposed hydrogel and novel implantation technique together represent a therapeutic approach with translational potential for replacing and regenerating diseased corneal stromal tissue.

Treatment for the osteochondral defects (ODs) is more challenging nowadays that needs to be addressed by developing alternative bone tissue engineering materials. Gellan gum (GG) is a widely used natural polysaccharide in the field of tissue engineering (TE) and regenerative medicine due to its versatile properties. There are many reports about the successful application of GG in cartilage tissue engineering and guiding bone formation. Functional coatings and porous composite materials have been introduced in next-generation materials for treating OD, whereas osteoconductive materials, such as demineralized bone particle (DBP) or bone derivatives, are used. However, modification of porosity, biocompatibility, cell proliferation, and mechanical properties is needed. DBP can activate human mesenchymal stem cells to differentiate into osteoblast cells. In this chapter, the potential application of GG with DBP in different combinations was reviewed, and the best suitable combinations were selected and further studied in small animal models for the soft and hard tissue engineering applications; also its application in the osteochondral integration fields were briefly discussed.

Collagen is an important component that makes 25–35% of our body proteins. Over the past decades, tissue engineers have been designing collagen-based biocompatible materials and studying their applications in different fields. Collagen obtained from cattle and pigs has been mainly used until now, but collagen derived from fish and other livestock has attracted more attention since the outbreak of mad cow disease, and they are also used as a raw material for cosmetics and foods. Due to the zoonotic infection using collagen derived from pigs and cattle, their application in developing biomaterials is limited; hence, the development of new animal-derived collagen is required. In addition, there is a religion (Islam, Hinduism, and Judaism) limited to export raw materials and products derived from cattle and pig. Hence, high-value collagen that is universally accessible in the world market is required. Therefore, in this review, we have dealt with the use of duck’s feet-derived collagen (DC) as an emerging alternative to solve this problem and also presenting few original investigated bone regeneration results performed using DC.