The biological effect of recombinant humanized collagen on damaged skin induced by UV-photoaging: An in vivo study

Food Safety Evaluation of Recombinant Humanized Type III Collagen Produced by Komagataella phaffii SMD1168-2COL3

Collagens are biofunctional proteins that have been widely used in many fields, including biomedical, cosmetics, and skin care for their value in maintaining the integrity of cellular membranes. Collagens are also commonly consumed in foods and provide a source of protein and amino acids. As part of the safety assessment for this particular recombinant humanized type III (RHTypeIII) collagen produced by Komagataella phaffii SMD1168-2COL3, a series of toxicological tests were conducted. This collagen has ≥ 90% amino acid sequence homology to bovine and porcine collagen. The RHTypeIII collagen showed no evidence of genotoxic potential in a battery of tests. It was not toxic in an acute oral study, with no effects at 10 g/kg BW. The RHTypeIII collagen was not developmentally toxic in Sprague Dawley (SD) rat, and the NOAEL was 4.5 g/kg BW/day. In a 90-day oral gavage study in rats, there were no adverse findings observed; therefore, the high dose level (4.5 g/kg BW/day) was considered the NOAEL. The protein sequence was subjected to homology searches against the AllergenOnline database (sliding 80-amino acid windows and full sequence searches). From the 80-amino acid alignment searches, 23 significant matches were identified (> 35% identity and E value < 1 × 10-7) to allergens of bovine, fish, anisakis, feverfew pollen, ragweed pollen, and wheat origin. Although matches were identified, further assessment of the in silico results combined with a literature review demonstrates that the risk of allergenic cross-reactivity for this collagen is low. These results demonstrate RHTypeIII collagen is not toxic and unlikely to present a risk of allergy when used as a food ingredient.

Recombinant Type III Humanized Collagen Solution for Injection Promotes Skin Repair in Chinese Population: A Case Series

BACKGROUND

Facial erythema and acne scarring are common skin conditions that significantly impair quality of life, necessitating effective treatment options, particularly in Asian populations.

AIMS

To evaluate the efficacy and safety of intradermal injections of recombinant type III humanized collagen (RhCol-III) solution for alleviating facial erythema, improving skin texture associated with acne scarring, and evening out skin tone issues associated with post-inflammatory hyperpigmentation (PIH) from acne while also searching for potential underlying anti-inflammatory mechanisms of the RhCol-III solution.

METHODS

This case series included six Chinese participants with Fitzpatrick phototypes III/IV, presenting with facial erythema and/or acne scarring. Participants received intradermal injections of 2 mg/mL RhCol-III solution at baseline, 30- and 60- days post-baseline. Clinical evaluations were conducted using VISIA photography and self-assessed Global Aesthetic Improvement Scale (GAIS) scores. Additionally, in vitro testing was performed using the U937 cell line with lipopolysaccharide (LPS) induction to assess the anti-inflammatory effects of the RhCol-III solution on tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) secretion.

RESULTS

All participants demonstrated a reduction in facial erythema post-treatment, with significant improvements noted in the zygomatic area. The mean erythema area decreased by 49.3% after 90 days. One case with acne scarring showed visible improvement in scar appearance, skin tone, and texture. Moreover, 0.10 mg/mL RhCol-III solution significantly reduced TNF-α and IL-6 levels in vitro by up to 47.75% and 44.96%, respectively.

CONCLUSION

RhCol-III solution injections effectively reduced facial erythema and have the potential to improve acne scarring via reduction in the extent of PIH in this series of Chinese cases. The treatment was well-tolerated, with no significant adverse effects. These findings suggest RhCol-III solution as a promising therapeutic option for skin repair and inflammation reduction.

Advancements in Clinical Utilization of Recombinant Human Collagen: An Extensive Review

INTRODUCTION

Recombinant human collagen, developed through advanced recombinant DNA technology, has emerged as a cutting-edge biomaterial with diverse applications in medicine. It addresses significant limitations of animal-derived collagens, such as immunogenicity and the risk of zoonotic diseases.

OBJECTIVE

This review evaluates the clinical applications, benefits, and challenges associated with recombinant human collagen, focusing on its potential to transform medical and surgical practices.

METHODS

A comprehensive search was conducted in MEDLINE, PubMed, and Ovid databases using keywords such as "Recombinant Human Collagen", "Collagen-Based Biomaterials", "Clinical Applications", "Tissue Repair", and "Wound Healing". Relevant studies, including clinical trials and diagnostic applications, were analyzed and classified according to the Oxford Centre for Evidence-Based Medicine evidence hierarchy.

FINDINGS

Recombinant human collagen demonstrates superior mechanical properties and controlled degradation rates compared to traditional collagen sources. Clinical studies highlight its effectiveness in accelerating wound closure, promoting dermal regeneration, and minimizing scarring, making it particularly valuable in chronic wound management and surgical interventions. In tissue engineering, recombinant human collagen scaffolds have shown potential for regenerating cartilage, bone, and cardiovascular tissues by supporting cell proliferation, differentiation, and matrix deposition. Additionally, its adaptability for forming hydrogels and matrices enhances its suitability for drug delivery systems, enabling controlled and sustained release of therapeutic agents.

CONCLUSION

Recombinant human collagen represents a transformative advancement in clinical practice, providing a safer and more effective alternative to traditional collagen sources. Its demonstrated success in wound healing, tissue engineering, and drug delivery highlights its potential to significantly improve patient outcomes. However, challenges such as high production costs, regulatory complexities, and long-term biocompatibility remain barriers to widespread clinical adoption. Further research and collaboration between biotechnology developers and regulatory authorities are essential to fully realize its clinical potential.

Injection of Different Concentrations of Recombinant Humanized Type III Collagen Into the Dermis Promotes Type III and Type I Collagen Deposition as Well as Angiogenesis: An In Vivo Study

BACKGROUND

Type III recombinant humanized collagen (rhCol III) has a promising future in cosmetic applications.

OBJECTIVE

To investigate the histological changes associated with injection of different concentrations of Type III rhCol III into the dermis.

MATERIALS AND METHODS

Twenty mice were divided into a control, low-dose (LD) group, and high-dose (HD) group. The animals were euthanized 1, 2, 3, and 4 weeks after the injection.

RESULTS

Injections of rhCol III induced an increase in collagen formation in a concentration-dependent manner. Type I collagen (Col I) was upregulated in both HD and LD groups to varying extents, often similar to that of Col III. Fibroblast proliferation plays an important role in the deposition of Col I and Col III. Injections of rhCol III promoted angiogenesis at later stages, regardless of concentration dependency.

CONCLUSION

Intradermal injections of rhCol III can promote fibroblast proliferation, enhancing the deposition of both Col I and Col III, and stimulating angiogenesis. Further studies are required to elucidate the mechanisms.

Self-Cross-Linked Collagen Sponge from the Alosa sapidissima Scale for Hemostasis and Wound Healing Applications

Type I collagen, a crucial component maintaining the structural integrity and physiological function of various tissues, is widely regarded as one of the most suitable biomaterials for healthcare applications. In this study, shad scales, used for treating ulcers, scalds, and burns in traditional Chinese medicine, were exploited for type I collagen extraction. After self-assembly into hydrogels, the extracted collagen was subsequently freeze-dried to form collagen sponges. The collagen sponge promoted rapid hemostasis, neovascularization, and immune regulation. Additionally, it accelerated the formation of granulation tissue, re-epithelialization, and collagen remodeling at the wound site in full-thickness skin wound rat models. Consequently, the shad scale collagen sponge holds great promise for the treatment of chronic wounds and skin regeneration. Notably, the shad was sourced from sustainably recirculating aquaculture systems (RAS) farms that adhere to the Traceable Management of Animal Products Safety, ensuring that the derived collagen possesses potential in the medical apparatus market.

Comparing the Effectiveness of Platelet-Rich Plasma Alone Versus Combined With Microneedles or Radiofrequency for Neck Wrinkle Treatment

BACKGROUND

Neck wrinkles are a prominent characteristic of skin aging, with recent studies indicating that interventions such as platelet-rich plasma (PRP), microneedling (MN), and radiofrequency (RF) can effectively rejuvenate aging skin.

AIMS

This study aims to assess and compare the efficacy of three treatment modalities in addressing neck wrinkles.

METHODS

Fifteen female participants with a neck Lemperle Wrinkle Assessment Scale (WAS) score of 3-4 were enrolled in a randomized clinical trial. The subjects were randomly assigned to three treatment groups: PRP injection, MN + PRP topical PRP application, and RF + PRP injection. They received treatment once a month for three consecutive months, and a clinical outcome evaluation was performed at 1 and 6 months after the final treatment.

RESULTS

The WAS scores and global aesthetic improvement score (GAIS) demonstrated notable enhancements 1 month postfinal treatment across all three groups, with a notably greater number of participants experiencing improved outcomes in the RF + PRP group 6 months posttreatment. Specifically, at the 1-month follow-up, the RF + PRP group exhibited a statistically significant enhancement in skin elasticity and collagen, surpassing the improvements observed in the other two groups (p < 0.05). No significant disparities in skin elasticity and collagen were detected in all groups prior to and after 6 months of treatment. Adverse events were mild and transient, such as redness, swelling, bruising, and pain.

CONCLUSION

This study revealed that all the treatments can effectively improve neck wrinkles 1 month after the last treatment. A better therapeutic effect could be observed in the RF + PRP group compared with the other two groups at 6 months after the last treatment.

A ROS-Responsive Lipid Nanoparticles Release Multifunctional Hydrogel Based on Microenvironment Regulation Promotes Infected Diabetic Wound Healing

The continuous imbalance of the diabetic wound microenvironment is an important cause of chronic nonhealing, which manifests as a vicious cycle between excessive accumulation of reactive oxygen species (ROS) and abnormal healing. Regulating the microenvironment by suppressing wound inflammation, oxidative stress, and bacterial infection is a key challenge in treating diabetic wounds. In this study, ROS-responsive hydrogels are developed composed of silk fibroin methacrylated (SFMA), modified collagen type III (rCol3MA), and lipid nanoparticles (LNPs). The newly designed hydrogel system demonstrated stable physicochemical properties and excellent biocompatibility. Moreover, the release of antimicrobial peptide (AMP) and puerarin (PUE) demonstrated remarkable efficacy in eradicating bacteria, regulating inflammatory responses, and modulating vascular functions. This multifunctional hydrogel is a simple and efficient approach for the treatment of chronic diabetic infected wounds and holds tremendous potential for future clinical applications.

Recent Developments in Using Microneedle Patch Technology as a More Efficient Drug Delivery System for Treating Skin Photoaging

Skin photoaging, resulting from prolonged exposure to ultraviolet (UV) radiation, is characterized by intricate biological changes involving oxidative damage and structural alterations. Despite an increasing demand for effective interventions, the current therapeutic options for treating skin photoaging are limited. We discovered through literature data search on PubMed that recent research has shifted its focus to the application of microneedle patches as an innovative approach to address this concern. Microneedle patches, serving as a novel transdermal delivery system, exhibit the potential to deliver bioactive substances such as cytokines, cellular vesicles, gene fragments and even alive algae to mitigate the effects of skin photoaging. This review aims to provide a comprehensive overview of recent advancements in research about utilizing microneedle patches for the treatment of skin photoaging and potential future directions in leveraging microneedle patches as clinical therapeutic agents for skin rejuvenation. Ultimately, we believe that microneedle patches have a broader application prospect in the fields of medical cosmetology and anti-photoaging.

Collaborative Enhancement of Diabetic Wound Healing and Skin Regeneration by Recombinant Human Collagen Hydrogel and hADSCs

Stem cell-based therapies hold significant promise for chronic wound healing and skin appendages regeneration, but challenges such as limited stem cell lifespan and poor biocompatibility of delivery systems hinder clinical application. In this study, an in situ delivery system for human adipose-derived stem cells is developed (hADSCs) to enhance diabetic wound healing. The system utilizes a photo-crosslinking recombinant human type III collagen (rHCIII) hydrogel to encapsulate hADSCs, termed the hADSCs@rHCIII hydrogel. This hydrogel undergoes local crosslinking at the wound site, establishing a sturdy 3D niche suitable for stem cell function. Consequently, the encapsulated hADSCs exhibit strong attachment and spreading within the hydrogels, maintaining their proliferation, metabolic activity, and viability for up to three weeks in vitro. Importantly, in vivo studies demonstrate that the hADSCs@rHCIII hydrogel achieves significant in situ delivery of stem cells, prolonging their retention within the wound. This ultimately enhances their immunomodulatory capabilities, promotes neovascularization and granulation tissue formation, facilitates matrix remodeling, and accelerates healing in a diabetic mouse wound model. Collectively, these findings highlight the potential of the conveniently-prepared and user-friendly hADSCs@rHCIII hydrogel as a promising therapeutic approach for diabetic wound treatment and in situ skin regeneration.

Tailoring biomaterials for skin anti-aging

Skin aging is the phenomenon of degenerative changes in the structure and function of skin tissues over time and is manifested by a gradual loss of skin elasticity and firmness, an increased number of wrinkles, and hyperpigmentation. Skin anti-aging refers to a reduction in the skin aging phenomenon through medical cosmetic technologies. In recent years, new biomaterials have been continuously developed for improving the appearance of the skin through mechanical tissue filling, regulating collagen synthesis and degradation, inhibiting pigmentation, and repairing the skin barrier. This review summarizes the mechanisms associated with skin aging, describes the biomaterials that are commonly used in medical aesthetics and their possible modes of action, and discusses the application strategies of biomaterials in this area. Moreover, the synergistic effects of such biomaterials and other active ingredients, such as stem cells, exosomes, growth factors, and antioxidants, on tissue regeneration and anti-aging are evaluated. Finally, the possible challenges and development prospects of biomaterials in the field of anti-aging are discussed, and novel ideas for future innovations in this area are summarized.

Human adipose mesenchymal stem cell-derived exosomes alleviate fibrosis by restraining ferroptosis in keloids

Background

Keloid is a fibroproliferative disease with unsatisfactory therapeutic effects and a high recurrence rate. exosomes produced by adipose-derived mesenchymal stem cells (ADSC-Exos) have attracted significant interest due to their ability to treat fibrosis. However, the molecular mechanisms of ADSC-Exos in keloids remain inconclusive.

Objective

Our study revealed the relationship between ferroptosis and fibrosis in keloids. Subsequently, this study aimed to explore further the anti-fibrotic effect of ADSC-Exos on keloids through ferroptosis and the potential underlying mechanisms.

Methods

To investigate the impact of ferroptosis on keloid fibrosis, Erastin and ferrostatin-1 (fer-1) were utilized to treat keloid fibroblast. Keloid keloids treated with Erastin and fer-1 were cocultured with ADSC-Exos to validate the impact of ferroptosis on the effect of ADSC-Exos on keloid anti-ferrotic protein, peroxidase 4 (GPX4) and anti-fibrotic effects in vivo and in vitro by Western blot, as well as variations in iron metabolite expression, malondialdehyde (MDA), liposomal peroxidation (LPO) and glutathione (GSH) were analyzed. The effect of solute carrier family 7-member 11 (SLC7A11) silencing on ADSC-Exo-treated keloid fibroblast was investigated.

Results

Iron metabolite dysregulation was validated in keloids. Fibrosis progression is enhanced by Erastin-induced ferroptosis. The anti-fibrotic effects of ADSC-Exos and fer-1 are related to their ability to prevent iron metabolism. ADSC-Exos effectively suppressed keloid fibrosis progression and increased GSH and GPX4 gene expression. Additionally, the use of Erastin limits the effect of ADSC-Exos in keloids. Furthermore, the effect of ADSC-Exos on keloids was associated with SLC7A11-GPX4 signaling pathway.

Conclusion

We demonstrated a new potential mechanism by which anti-ferroptosis inhibits the progression of keloid fibrosis and identified an ADSC-Exo-based keloid therapeutic strategy. Resisting the occurrence of ferroptosis and the existence of the SLC7A11-GPX4 signaling pathway might serve as a target for ADSC-Exos.

Recombinant fibrous protein biomaterials meet skin tissue engineering

Natural biomaterials, particularly fibrous proteins, are extensively utilized in skin tissue engineering. However, their application is impeded by batch-to-batch variance, limited chemical or physical versatility, and environmental concerns. Recent advancements in gene editing and fermentation technology have catalyzed the emergence of recombinant fibrous protein biomaterials, which are gaining traction in skin tissue engineering. The modular and highly customizable nature of recombinant synthesis enables precise control over biomaterial design, facilitating the incorporation of multiple functional motifs. Additionally, recombinant synthesis allows for a transition from animal-derived sources to microbial sources, thereby reducing endotoxin content and rendering recombinant fibrous protein biomaterials more amenable to scalable production and clinical use. In this review, we provide an overview of prevalent recombinant fibrous protein biomaterials (collagens, elastin, silk proteins and their chimeric derivatives) used in skin tissue engineering (STE) and compare them with their animal-derived counterparts. Furthermore, we discuss their applications in STE, along with the associated challenges and future prospects.

Expression, characterization, and application of human-like recombinant gelatin

Gelatin is a product obtained through partial hydrolysis and thermal denaturation of collagen, belonging to natural biopeptides. With irreplaceable biological functions in the field of biomedical science and tissue engineering, it has been widely applied. The amino acid sequence of recombinant human-like gelatin was constructed through a newly designed hexamer composed of six protein monomer sequences in series, with the minimum repeating unit being the characteristic Gly-X-Y sequence found in type III human collagen α1 chain. The nucleotide sequence was subsequently inserted into the genome of Pichia pastoris to enable soluble secretion expression of recombinant gelatin. At the shake flask fermentation level, the yield of recombinant gelatin is up to 0.057 g/L, and its purity can rise up to 95% through affinity purification. It was confirmed in the molecular weight determination and amino acid analysis that the amino acid composition of the obtained recombinant gelatin is identical to that of the theoretically designed. Furthermore, scanning electron microscopy revealed that the freeze-dried recombinant gelatin hydrogel exhibited a porous structure. After culturing cells continuously within these gelatin microspheres for two days followed by fluorescence staining and observation through confocal laser scanning microscopy, it was observed that cells clustered together within the gelatin matrix, exhibiting three-dimensional growth characteristics while maintaining good viability. This research presents promising prospects for developing recombinant gelatin as a biomedical material.

Controllable self-assembly of tyrosine-rich triblock peptides into robust collagen mimetic bioscaffolds for aging skin rejuvenation

Skin aging, a complex physiological process characterized by alterations in skin structure and function, seriously affects human life. Collagen holds considerable potential in aging skin treatment, while animal-derived collagen poses risks of pathogen transmission. Self-assembled peptides have garnered increasing attention in creating collagen mimetic materials; however, previous reported self-assembled peptides rely on vulnerable non-covalent interactions or lack the capability of controlling morphology and incorporating functional motifs, limiting their ability to mimic collagen structure and function. We have herein created a controllable tyrosine-rich triblock peptide system capable of self-assembling into robust collagen mimetic bioscaffolds for rejuvenating aging skin. Through ruthenium-mediated crosslinking, these peptides self-assemble into well-defined nanospheres or collagen-mimetic scaffolds, precisely regulated by the triple-helical structure and tyrosine distribution. The self-assembled collagen mimetic scaffolds exhibit outstanding resistances to various solvents and pH conditions. The integrin-binding motif has been incorporated into the triple helical block without disrupting their assembly, while endowing them with superior bioactivities, effectively promoting cell adhesion and proliferation. In vivo studies demonstrated their efficacy in treating photoaging skin by accelerating collagen regeneration and activating fibroblasts. The self-assembled tyrosine-rich triblock peptides represent a versatile system for creating robust collagen mimetic biomaterials, providing great potential in skin rejuvenation and tissue regeneration.

Lignin-Based Antioxidant Hydrogel Patch for the Management of Atopic Dermatitis by Mitigating Oxidative Stress in the Skin

Atopic dermatitis (AD), a chronic skin condition characterized by itching, redness, and inflammation, is closely associated with heightened levels of endogenous reactive oxygen species (ROS) in the skin. ROS can contribute to the onset and progression of AD through oxidative stress, which leads to the release of proinflammatory cytokines, T-cell differentiation, and the exacerbation of skin symptoms. In this study, we aim to develop a therapeutic antioxidant hydrogel patch for the potential treatment of AD using lignin, a biomass waste material. Lignin contains polyphenol groups that enable it to scavenge ROS and exhibit antioxidant properties. The lignin hydrogel patches, possessing optimized mechanical properties through the control of the lignin and cross-linker ratio, demonstrated high ROS-scavenging capabilities. Furthermore, the lignin hydrogel demonstrated excellent biocompatibility with the skin, exhibiting beneficial properties in protecting human keratinocytes under high oxidative conditions. When applied to an AD mouse model, the hydrogel patch effectively reduced epidermal thickness in inflamed regions, decreased mast cell infiltration, and regulated inflammatory cytokine levels. These findings collectively suggest that lignin serves as a therapeutic hydrogel patch for managing AD by modulating oxidative stress through its ROS-scavenging ability.

Preparation of an injectable and photocurable carboxymethyl cellulose/hydroxyapatite composite and its application in cranial regeneration

Limited bone regeneration, uncontrollable degradation rate, mismatched defect zone and poor operability have plagued the reconstruction of irregular bone defect by tissue-engineered materials. A combination of biomimetic scaffolds with hydroxyapatite has gained great popularity in promoting bone regeneration. Therefore, we designed an injectable, photocurable and in-situ curing hydrogel by methacrylic anhydride -modified carboxymethyl cellulose (CMC-MA) loading with spherical hydroxyapatite (HA) to highly simulate the natural bony matrix and match any shape of damaged tissue. The prepared carboxymethyl cellulose-methacrylate/ hydroxyapatite(CMC-MA/HA) composite presented good rheological behavior, swelling ratio and mechanical property under light illumination. Meanwhile, this composite hydrogel promoted effectively proliferation, supported adhesion and upregulated the osteogenic-related genes expression of MC3T3-E1 cells in vitro, as well as the activity of the osteogenic critical protein, Integrin α1, β1, Myosin 9, Myosin 10, BMP-2 and Smad 1 in Integrin/BMP-2 signal pathway. Together, the composite hydrogels realized promotion of bone regeneration, deformity improvement, and the enhanced new bone strength in skull defect. It also displayed a good histocompatibility and stability of subcutaneous implantation in vivo. Overall, this study laid the groundwork for future research into developing a novel biomaterial and a minimally invasive therapeutic strategies for reconstructing bone defects and contour deficiencies.

Recombination humanized type III collagen promotes oral ulcer healing

OBJECTIVE

Recombinant humanized type III collagen (rhCol III) is a highly adhesive biomaterial composed of 16 adhesion-related tandem repeats refined from human type III collagen. Here, we aimed to investigate the effect of rhCol III on oral ulcers and reveal the underlying mechanism.

METHODS

Acid-induced oral ulcers were induced on the murine tongue, and rhCol III or saline drops were administered. The effect of rhCol III on oral ulcers was assessed using gross and histological analyses. The effects on the proliferation, migration, and adhesion of human oral keratinocytes were investigated in vitro. The underlying mechanism was explored using RNA sequencing.

RESULTS

Administration of rhCol III accelerated the lesion closure of oral ulcers, reduced the release of inflammatory factors, and alleviated pain. rhCol III promoted the proliferation, migration, and adhesion of human oral keratinocytes in vitro. Mechanistically, the enrichment of genes associated with the Notch signaling pathway was upregulated after rhCol III treatment.

CONCLUSION

rhCol III promoted the healing of oral ulcers, showing promising therapeutic potential in oral clinics.

Effect of atomization on the composition and structure of recombinant humanized collagen type III

Atomization is a treatment method to make inhaled liquids into aerosols and transport them to target organs in the form of fog or smoke. It has the advantages of improving the bioavailability of drugs, being painless, and non-invasive, and is now widely used in the treatment of lung and oral lesions. Aerosol inhalation as the route of administration of therapeutic proteins holds significant promise due to its ability to achieve high bioavailability in non-invasive pathways. Currently, a great number of therapeutic proteins such as alpha-1 antitrypsin and Dornase alfa are effective. Recombinant humanized collagen type III (rhCol III) as a therapeutic protein is widely used in the biomedical field, but atomization is not a common route of administration for rhCol III, presenting great potential for development. However, the structural stability of recombinant humanized collagen after atomization needs further investigation. This study demonstrated that the rhCol III subjected to atomization through compressed air had retained its original molecular weights, triple helical structures, and the ability to promote cell adhesion. In other words, the rhCol III can maintain its stability after undergoing atomization. Although more research is required to determine the efficacy and safety of the rhCol III after atomization, this study can lay the groundwork for future research.

Collagen study advances for photoaging skin

BACKGROUND

Collagen dominates the skin's extracellular matrix (ECM). Type I collagen comprises 80%-90% of the skin's collagen, followed by type III (8%-12%) and type V (5%). Reactive oxygen species, matrix metalloproteinases, and collagen degradation all increase during photoaging, which disrupts the ECM's dynamic balance and lowers the amount of total collagen in the body. In recent years, domestic and foreign researchers have conducted multidimensional and multifaceted studies on collagen and skin photoaging. Collagen and the peptides that are derivates of it are currently being used more and more in biomedicine and medical esthetics.

OBJECTIVE

Offering new suggestions for both the avoidance and remedy of photoaging.

METHODS

This article reviews collagen and its potential connection to skin photoaging, illustrates the effects of collagen and peptide supplementation derivatives on photoaged skin, and briefly describes other compounds that can also be used to fight photoaging by increasing collagen synthesis in the skin.

RESULT

Both internal and external aging are inevitable, and as the main component of extracellular matrix, collagen plays a variety of functions in maintaining skin structure and fighting skin aging, and its role in photoaging is undeniable. Ultraviolet radiation can induce increased fragmentation and degradation of cutaneous collagen, while conversely, supplementation with collagen can effectively counteract photodamage-induced skin impairment.

CONCLUSION

Collagen and its derived peptides are indispensable in photoaging skin, holding promising prospects for applications in skin aging.

Sodium alginate hydrogel integrated with type III collagen and mesenchymal stem cell to promote endometrium regeneration and fertility restoration

A thinner endometrium has been linked to implantation failure, and various therapeutic strategies have been attempted to improve endometrial regeneration, including the use of mesenchymal stem cells (MSCs). However, low survival and retention rates of transplanted stem cells are main obstacles to efficient stem cell therapy in thin endometrium. Collagen type III is a key component of the extracellular matrix, plays a crucial role in promoting cell proliferation and differentiation, and has been identified as the major collagen expressed at the implantation site. Herein, composite alginate hydrogel containing recombinant type III collagen (rCo III) and umbilical cord mesenchymal stem cells are developed. rCo III serves as favorable bioactive molecule, displaying that rCo III administration promotes MSCs proliferation, stemness maintenance and migration. Moreover, rCo III administration enhances cell viability and migration of mouse endometrial stromal cells (ESCs). In a mouse model of thin endometrium, the Alg-rCo III hydrogel loaded with MSCs (MSC/Alg-rCo III) significantly induces endometrial regeneration and fertility enhancement in vivo. Further studies demonstrate that the MSC/Alg-rCo III hydrogel promoted endometrial function recovery partly by regulating mesenchymal-epithelial transition of ESCs. Taken together, the combination of Alg-rCo III hydrogel and MSCs has shown promising results in promoting endometrium regeneration and fertility restoration, and may provide new therapeutic options for endometrial disease.

Injectable self-assembled dual-crosslinked alginate/recombinant collagen-based hydrogel for endometrium regeneration

The disadvantages of mainstream therapies for endometrial injury are difficult to resolve, herein, we suggest an omnibearing improvement strategy by introducing an injectable multifunctional self-assembled dual-crosslinked sodium alginate/recombinant collagen hydrogel. The hydrogel possessed a reversible and dynamic double network based on dynamic covalent bonds and ionic interactions, which also contributed to excellent capability in viscosity and injectability. Moreover, it was also biodegradable with a suitable speed, giving off active ingredients during the degradation process and eventually disappearing completely. In vitro tests exhibited that the hydrogel was biocompatible and able to enhance endometrial stromal cells viability. These features synergistically promoted cell multiplication and maintenance of endometrial hormone homeostasis, which accelerated endometrial matrix regeneration and structural reconstruction after severe injury in vivo. Furthermore, we explored the interrelation between the hydrogel characteristics, endometrial structure, and postoperative uterine recovery, which would benefit deep research on regulation of uterine repair mechanism and optimization of hydrogel materials. The injectable hydrogel could achieve favourable therapeutic efficacy without the need of exogenous hormones or cells, which would be of clinical value in endometrium regeneration.

Characterization of recombinant humanized collagen type III and its influence on cell behavior and phenotype

Collagen made a tremendous impact in the field of regenerative medicine as a bioactive material. For decades, collagen has been used not only as a scaffolding material but also as an active component in regulating cells' biological behavior and phenotype. However, animal-derived collagen as a major source suffered from problems of immunogenicity, risk of viral infection, and the unclear relationship between bioactive sequence and function. Recombinant humanized collagen (rhCol) provided alternatives for regenerative medicine with more controllable risks. However, the characterization of rhCol and the interaction between rhCol and cells still need further investigation, including cell behavior and phenotype. The current study preliminarily demonstrated that recombinant humanized collagen type III (rhCol III) conformed to the theoretical amino acid sequence and had an advanced structure resembling bovine collagen. Furthermore, rhCol III could facilitate basal biological behaviors of human skin fibroblasts, such as adhesion, proliferation and migration. rhCol III was beneficial for some extracellular matrix-expressing cell phenotypes. The study would shed light on the mechanism research of rhCol and cell interactions and further understanding of effectiveness in tissue regeneration.

Graphical abstract

Translation of biomaterials from bench to clinic

Scientific research originates from curiosity and interests. Translational research of biomaterials should always focus on addressing specific needs of the targeted clinical applications. The guest editors of this special issue hope that the included articles have provided cutting-edge biomaterials research as well as insights of the translation of biomaterials from bench to clinic.

Advanced application of collagen-based biomaterials in tissue repair and restoration

In tissue engineering, bioactive materials play an important role, providing structural support, cell regulation and establishing a suitable microenvironment to promote tissue regeneration. As the main component of extracellular matrix, collagen is an important natural bioactive material and it has been widely used in scientific research and clinical applications. Collagen is available from a wide range of animal origin, it can be produced by synthesis or through recombinant protein production systems. The use of pure collagen has inherent disadvantages in terms of physico-chemical properties. For this reason, a processed collagen in different ways can better match the specific requirements as biomaterial for tissue repair. Here, collagen may be used in bone/cartilage regeneration, skin regeneration, cardiovascular repair and other fields, by following different processing methods, including cross-linked collagen, complex, structured collagen, mineralized collagen, carrier and other forms, promoting the development of tissue engineering. This review summarizes a wide range of applications of collagen-based biomaterials and their recent progress in several tissue regeneration fields. Furthermore, the application prospect of bioactive materials based on collagen was outlooked, aiming at inspiring more new progress and advancements in tissue engineering research.

Graphical Abstract

High-efficiency secretory expression and characterization of the recombinant type III human-like collagen in Pichia pastoris

Collagen, the highest content protein in the body, has irreplaceable biological functions, and it is widespread concerned in food, beauty, and medicine with great market demand. The gene encoding the recombinant type III human-like collagen α1 chain fragment was integrated into P. pastoris genome after partial amino acids were substituted. Combined with promoter engineering and high-density fermentation technology, soluble secretory expression with the highest yield of 1.05 g L-1 was achieved using two-stage feeding method, and the purity could reach 96% after affinity purification. The determination of N/C-terminal protein sequence were consistent with the theoretical expectation and showed the characteristics of Gly-X-Y repeated short peptide sequence. In amino acid analysis, glycine shared 27.02% and proline 23.92%, which were in accordance with the characteristics of collagen. Ultraviolet spectrum combined with Fourier transform infrared spectroscopy as well as mass spectrometry demonstrated that the target product conformed to the characteristics of collagen spectrums and existed as homologous dimer and trimer in the broth. This work provided a sustainable and economically viable source of the recombinant type III human-like collagen.

Photoprotective effects of sweet potato leaf polyphenols and caffeic acid against UV-induced skin-damage in BALB/C nude mice

This study aimed at clarifying the mechanism by which sweet potato leaf polyphenols (SPLPs) ameliorate ultraviolet (UV) radiation damage, using the BALB/c hairless female mouse model. The moisture and hydroxyproline (HYP) contents of the model mouse skin and the thickness of the epidermis and dermis were determined by staining and histological examination. Anti-oxidative enzyme activities, malondialdehyde (MDA) content, and protein carbonyl content in skin tissue and serum were investigated. Expression of inflammatory markers and mitogen-activated protein kinase signaling pathways were evaluated. Topical caffeic acid at 30 mg kg^-1 most strongly inhibited the decrease in skin moisture, HYP content, and the thickening of the epidermis. Topical SPLP at 100 mg kg^-1 most significantly inhibited the dermal thickening, increased the activities of the superoxide dismutase, catalase as well as glutathione peroxidase, and decreased the content of serum MDA and protein carbonyls markedly. Furthermore, the topical SPLP suppressed the UV-induced rise in the inflammatory markers MMP-1, TNF-α, and NF-κB, and alleviated phosphorylation levels of the stress-signaling proteins JNK and p38. Thus, topical SPLP provided the best overall protection for mouse skin from UV-induced damage.

Preparation of Recombinant Human Collagen III Protein Hydrogels with Sustained Release of Extracellular Vesicles for Skin Wound Healing

Existing treatment methods encounter difficulties in effectively promoting skin wound healing, making this a serious challenge for clinical treatment. Extracellular vesicles (EVs) secreted by stem cells have been proven to contribute to the regeneration and repair of wound tissue, but they cannot be targeted and sustained, which seriously limits their current therapeutic potential. The recombinant human collagen III protein (rhCol III) has the advantages of good water solubility, an absence of hidden viral dangers, a low rejection rate and a stable production process. In order to achieve a site-specific sustained release of EVs, we prepared a rhCol III hydrogel by cross-linking with transglutaminase (TGase) from Streptomyces mobaraensis, which has a uniform pore size and good biocompatibility. The release profile of the rhCol III-EVs hydrogel confirmed that the rhCol III hydrogel could slowly release EVs into the external environment. Herein, the rhCol III-EVs hydrogel effectively promoted macrophage changing from type M1 to type M2, the migration ability of L929 cells and the angiogenesis of human umbilical vein endothelial cells (HUVECs). Furthermore, the rhCol III-EVs hydrogel is shown to promote wound healing by inhibiting the inflammatory response and promoting cell proliferation and angiogenesis in a diabetic rat skin injury model. The reported results indicate that the rhCol III-EVs hydrogel could be used as a new biological material for EV delivery, and has a significant application value in skin wound healing.

A Preliminary Investigation of Embedding In Vitro HepaRG Spheroids into Recombinant Human Collagen Type I for the Promotion of Liver Differentiation

Background: In vitro three-dimensional (3D) hepatic spheroid culture has shown great promise in toxicity testing because it better mimics the cell–cell and cell–matrix interactions found in in vivo conditions than that of the traditional two-dimensional (2D) culture. Despite embedding HepaRG spheroids with collagen type I (collagen I) extracellular matrix (ECM) revealed a much better differentiation capability, almost all the collagen utilized in in vitro hepatocytes cultures is animal-derived collagen that may limit its use in human toxicity testing. Method: Here, a preliminary investigation of HepaRG cells cultured in different dimensionalities and with the addition of ECM was performed. Comparisons of conventional 2D culture with 3D spheroid culture were performed based on their functional or structural differences over 7 days. Rat tail collagen (rtCollagen) I and recombinant human collagen (rhCollagen) I were investigated for their ability in promoting HepaRG spheroid differentiation. Results: An immunofluorescence analysis of the hepatocyte-specific functional protein albumin suggested that HepaRG spheroids demonstrated better hepatic function than spheroids from 2D culture, and the function of HepaRG spheroids improved in a time-dependent manner. The fluorescence intensities per unit area of spheroids formed by 1000 cells on days 7 and 10 were 25.41 and 45.38, respectively, whereas almost undetectable fluorescence was obtained with 2D cells. In addition, the embedding of HepaRG spheroids into rtCollagen and rhCollagen I showed that HepaRG differentiation can be accelerated relative to the differentiation of spheroids grown in suspension, demonstrating the great promise of HepaRG spheroids. Conclusions: The culture conditions established in this study provide a potentially novel alternative for promoting the differentiation of HepaRG spheroids into mature hepatocytes through a collagen-embedded in vitro liver spheroid model. This culture method is envisioned to provide insights for future drug toxicology.