Collagen Scaffolds Research Articles

Narrative Review and Guide: State of the Art and Emerging Opportunities of Bioprinting in Tissue Regeneration and Medical Instrumentation

Three-dimensional printing was introduced in the 1980s, though bioprinting started developing a few years later. Today, 3D bioprinting is making inroads in medical fields, including the production of biomedical supplies intended for internal use, such as biodegradable staples. Medical bioprinting enables versatility and flexibility on demand and is able to modify and individualize production using several established printing methods. A great selection of biomaterials and bioinks is available, including natural, synthetic, and mixed options; they are biocompatible and non-toxic. Many bioinks are biodegradable and they accommodate cells so upon implantation, they integrate within the new environment. Bioprinting is suitable for printing tissues using living or viable components, such as collagen scaffolding, cartilage components, and cells, and also for printing parts of structures, such as teeth, using artificial man-made materials that will become embedded in vivo. Bioprinting is an integral part of tissue engineering and regenerative medicine. The addition of newly developed smart biomaterials capable of incorporating dynamic changes in shape depending on the nature of stimuli led to the addition of the fourth dimension of time in the form of changing shape to the three static dimensions. Four-dimensional bioprinting is already making significant inroads in tissue engineering and regenerative medicine, including new ways to create dynamic tissues. Its future lies in constructing partial or whole organ generation.

Role of phenytoin solution in the management of diabetic foot

Chronic ulcers and non-healing wounds present a significant public health and economic burden, particularly in aging populations. This study aimed to evaluate the efficacy of topical phenytoin in enhancing wound healing, focusing on its effects on fibroblast proliferation, neovascularization, and overall wound repair.A case study was conducted in the Department of Plastic Surgery at a tertiary care center in South India involving a 69-year-old male patient with a non-healing diabetic foot ulcer complicated by Charcot's joint. Regenerative therapy utilized a 5 mg/ml diluted phenytoin solution for wound irrigation, followed by the application of a two-layered collagen scaffold, sterile dressing, and immobilization.Topical application of phenytoin demonstrated a marked improvement in wound healing. Observed outcomes included enhanced granulation tissue formation, reduced inflammation, and improved epithelialization.This study highlights the potential of phenytoin as an accessible, cost-effective, and safe therapeutic agent for chronic wound management. By promoting fibroblast proliferation, inhibiting collagenase activity, and enhancing neovascularization, phenytoin significantly improves wound healing. These findings support the integration of phenytoin in clinical practice for non-healing ulcers, with a recommendation for larger-scale studies to validate its broader applicability.

Sternoclavicular Joint Reconstruction Using the Sternal Docking Technique

Background: Sternoclavicular joint (SCJ) dislocations may occur as the result of traumatic injury, ligamentous laxity, or chronic arthropathy. While initial management of anterior sternoclavicular dislocations is typically nonoperative treatment, patients with symptomatic chronic dislocation may benefit from reconstruction. In this video, we describe the sternal docking technique for SCJ reconstruction using a semitendinosus allograft augmented with a biologic collagen scaffold. Indications: Current indications for SCJ reconstruction include acute posterior dislocations, symptomatic chronic anterior dislocations, and cases of symptomatic arthropathies of the SCJ. Technique Description: In a lazy beach-chair position, a curvilinear incision is made over the anterior SCJ centered over the inferior portion of the joint. After exposure of the joint, the intra-articular disc and 5 mm of medial clavicle are resected. A 4-mm bur is used to open the intramedullary canal on the articular facet of the manubrium and the medial clavicle. Additional perforations to act as tunnels are made on the anterior aspects of the manubrium and medial clavicle both superiorly and inferiorly, and a small curved curette is used to widen the tunnels and connect them to their respective intramedullary canals to allow for graft passage. The semitendinosus graft is whipstitched to a biologic collagen shoestring scaffold and passed through the tunnels. The joint is reduced, and the graft is sutured together over the top of the medial clavicle with appropriate tension. Results: The sternal docking technique was successfully implemented for the reconstruction of a chronic anterior SCJ dislocation and allowed the patient to return to full pain-free activity by 16 weeks. Discussion: Chronic anterior SCJ dislocations may fail to respond to conservative treatment measures necessitating operative reconstruction. The sternal docking technique using semitendinosus allograft augmented with a biologic shoestring scaffold described here is a safe and effective reconstructive technique. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Intrafibrillar calcium carbonate mineralization of electrospinning polyvinyl alcohol/collagen films with improved mechanical and bioactive properties.

Collagen films play an essential role in guided bone-regeneration (GBR) techniques, which create space, promote cell adhesion, and induce osteogenic differentiation. It is therefore crucial to design appropriate GBR films to facilitate bone regeneration. However, current electrospun collagen scaffolds used as bioactive materials have limited clinical applications due to their poor mechanical properties. In this study, polyvinyl alcohol (PVA)/collagen (Col) films were electrospun by mixing PVA and type I collagen solution. For the first time, the intrafibrillar mineralization of aragonite nanocrystals within the PVA/Col fibrils was achieved, resulting in the formation of a hierarchical, bioactive film. The PVA/Col-CaCO3 film exhibited good mechanical properties, with hardness and Young's modulus values of 211.6 ± 0.1 MPa and 5.6 ± 1.7 GPa, respectively. Furthermore, bone marrow mesenchymal stem cells (BMSCs) inoculated onto the PVA/Col-CaCO3 film demonstrated robust adhesion and proliferation. The mineralized fibrils effectively stimulated the growth of BMSCs while suppressing cell apoptosis. Besides, the PVA/Col-CaCO3 film significantly induced the osteogenic differentiation of BMSCs, revealing its potential biomedical applications in hard tissue engineering.

Wood-Derived Hydrogels for Osteochondral Defect Repair.

Repairing cartilage tissue is a serious global challenge. Herein, we focus on wood skeletal structures that are highly porous for cell penetration yet have load-bearing strength, and aim to synthesize wood-derived hydrogels with the ability to regenerate cartilage tissues. The hydrogels were synthesized by wood delignification and the subsequent intercalation of citric acid (CA), which is involved in tricarboxylic acid cycles and essential for energy production, and N-acetylglucosamine (NAG), which is a cartilage glycosaminoglycan, among cellulose microfibrils. CA and NAG intercalation increased the amorphous region of the cellulose microfibrils and endowed them with flexibility while maintaining the skeletal structure of the wood. Consequently, the CA-NAG-treated wood hydrogels became twistable and bendable, and the acquired stiffness, compressive strength, water content, and cushioning characteristics were similar to those of the cartilage. In rabbit femur cartilage defects, CA-NAG-treated wood hydrogels induced the differentiation of surrounding cells into chondrocytes. Consequently, the CA-NAG-treated wood hydrogels repaired cartilage defects, whereas the collagen scaffolds, delignified wood materials, and CA-treated wood hydrogels did not. The CA-NAG-treated wood hydrogels exhibit superior structural and mechanical characteristics over conventional cellulose-fiber-containing scaffolds. Furthermore, the CA-NAG-treated wood hydrogels can effectively repair cartilage on their own, whereas conventional natural and synthetic polymeric materials need to be combined with cells and growth factors to achieve a sufficient therapeutic effect. Therefore, the CA-NAG-treated wood hydrogels successfully address the limitations of current therapies that either fail to repair articular cartilage or sacrifice healthy cartilage. To our knowledge, this is the pioneer study on the utilization of thinned wood for tissue engineering, which will contribute to solving both global health and environmental problems and to creating a sustainable society.

Fibroblasts modulate epithelial cell behavior within the proliferative niche and differentiated cell zone within a human colonic crypt model.

Colonic epithelium is situated above a layer of fibroblasts that provide supportive factors for stem cells at the crypt base and promote differentiation of cells in the upper crypt and luminal surface. To study the fibroblast-epithelial cell interactions, an in vitro crypt model was formed on a shaped collagen scaffold with primary epithelial cells growing above a layer of primary colonic fibroblasts. The crypts possessed a basal stem cell niche populated with proliferative cells and a differentiated, nondividing cell zone at the luminal crypt end. The presence of fibroblasts enhanced cell differentiation and accelerated the rate at which a high resistance epithelial cell layer formed relative to cultures without fibroblasts. The fibroblasts modulated cell proliferation within crypts increasing the number of crypts populated with proliferative cells but decreasing the total number of proliferative cells in each crypt. Bulk-RNA sequencing revealed 41 genes that were significantly upregulated and 190 genes that were significantly downregulated in cocultured epithelium relative to epithelium cultured without fibroblasts. This epithelium-fibroblast crypt model suggests bidirectional communication between the two cell types and has the potential to serve as a model to investigate fibroblast-epithelial cell interactions in health and disease.

Clinical application of mineralized collagen scaffolds in surgical treatment of skull defects

To explore the clinical application value of mineralized collagen (MC) bone scaffolds in repairing various types of skull defects, and to assess the suitability and repair effectiveness of porous MC (pMC) scaffolds, compact MC (cMC) scaffolds, and biphasic MC composite (bMC) scaffolds. A retrospective analysis was conducted on the clinical data of 105 patients who underwent skull defect repair with pMC, cMC, or bMC between October 2014 and April 2022. The cohort included 63 males and 42 females, ranging in age from 3 months to 55 years, with a median age of 22.7 years. Causes of defects included craniectomy after traumatic surgery in 37 cases, craniotomy in 58 cases, tumor recurrence or intracranial hemorrhage surgery in 10 cases. Appropriate MC scaffolds were selected based on the patient's skull defect size and age: 58 patients with defects <3 cm² underwent skull repair with pMC (pMC group), 45 patients with defects ≥3 cm² and aged ≥5 years underwent skull repair with cMC (cMC group), and 2 patients with defects ≥3 cm² and aged <5 years underwent skull repair with bMC (bMC group). Postoperative clinical follow-up and imaging examinations were conducted to evaluate bone regeneration, the biocompatibility of the repair materials, and the occurrence of complications. All 105 patients were followed up 3-24 months, with an average of 13 months. No material-related complication occurred in any patient, including skin and subcutaneous tissue infection, excessive ossification, and rejection. CT scans at 6 months postoperatively showed bone growth in all patients, and CT scans at 12 months postoperatively showed complete or near-complete resolution of bone defects in all patients, with 58 cases repaired in the pMC group. The CT values of the defect site and the contralateral normal skull bone in the pMC group at 12 months postoperatively were (1 123.74±93.64) HU and (1 128.14±92.57) HU, respectively, with no significant difference ( t=0.261, P=0.795). MC exhibits good biocompatibility and osteogenic induction ability in skull defect repair. pMC is suitable for repairing small defects, cMC is suitable for repairing large defects, and bMC is suitable for repairing pediatric skull defects.

In vitro culture of leukemic cells in collagen scaffolds and carboxymethyl cellulose-polyethylene glycol gel.

Chronic lymphocytic leukemia (CLL) is a common adult leukemia characterized by the accumulation of neoplastic mature B cells in blood, bone marrow, lymph nodes, and spleen. The disease biology remains unresolved in many aspects, including the processes underlying the disease progression and relapses. However, studying CLL in vitro poses a considerable challenge due to its complexity and dependency on the microenvironment. Several approaches are utilized to overcome this issue, such as co-culture of CLL cells with other cell types, supplementing culture media with growth factors, or setting up a three-dimensional (3D) culture. Previous studies have shown that 3D cultures, compared to conventional ones, can lead to enhanced cell survival and altered gene expression. 3D cultures can also give valuable information while testing treatment response in vitro since they mimic the cell spatial organization more accurately than conventional culture. In our study, we investigated the behavior of CLL cells in two types of material: (i) solid porous collagen scaffolds and (ii) gel composed of carboxymethyl cellulose and polyethylene glycol (CMC-PEG). We studied CLL cells' distribution, morphology, and viability in these materials by a transmitted-light and confocal microscopy. We also measured the metabolic activity of cultured cells. Additionally, the expression levels of MYC, VCAM1, MCL1, CXCR4, and CCL4 genes in CLL cells were studied by qPCR to observe whether our novel culture approaches lead to increased adhesion, lower apoptotic rates, or activation of cell signaling in relation to the enhanced contact with co-cultured cells. Both materials were biocompatible, translucent, and permeable, as assessed by metabolic assays, cell staining, and microscopy. While collagen scaffolds featured easy manipulation, washability, transferability, and biodegradability, CMC-PEG was advantageous for its easy preparation process and low variability in the number of accommodated cells. Both materials promoted cell-to-cell and cell-to-matrix interactions due to the scaffold structure and generation of cell aggregates. The metabolic activity of CLL cells cultured in CMC-PEG gel was similar to or higher than in conventional culture. Compared to the conventional culture, there was (i) a lower expression of VCAM1 in both materials, (ii) a higher expression of CCL4 in collagen scaffolds, and (iii) a lower expression of CXCR4 and MCL1 (transcript variant 2) in collagen scaffolds, while it was higher in a CMC-PEG gel. Hence, culture in the material can suppress the expression of a pro-apoptotic gene (MCL1 in collagen scaffolds) or replicate certain gene expression patterns attributed to CLL cells in lymphoid organs (low CXCR4, high CCL4 in collagen scaffolds) or blood (high CXCR4 in CMC-PEG).

Collagen scaffold-seeded iTenocytes accelerate the healing and functional recovery of Achilles tendon defects in a rat model.

Tendon injuries represent an ongoing challenge in clinical practice due to poor regenerative capacity, structure, and biomechanical function recovery of ruptured tendons. This study is focused on the assessment of a novel strategy to repair ruptured Achilles tendons in a Nude rat model using stem cell-seeded biomaterial. Specifically, we have used induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells (iMSCs) overexpressing the early tendon marker Scleraxis (SCX, iMSCSCX+, iTenocytes) in combination with an elastic collagen scaffold. Achilles tendon defects in Nude rat models were created by isolating the tendon and excising 3mm of the midsection. The Achilles tendon defects were then repaired with iTenocyte-seeded scaffolds, unseeded scaffolds, or suture only and compared to native Nude rat tendon tissue using gait analyses, biomechanical testing, histology, and immunohistochemistry. The results show faster functional recovery of gait in iTenocyte-seeded scaffold group comparing to scaffold only and suture only groups. Both iTenocyte-seeded scaffold and scaffold only treatment groups had improved biomechanical properties when compared to suture only treatment group, however no statistically significant difference was found in comparing the cell seeding scaffold an scaffold only group in terms of biomechanical properties. Immunohistochemistry staining further demonstrated that iTenocytes successfully populated the collagen scaffolds and survived 9weeks after implantation in vivo. Additionally, the repaired tissue of iTenocyte-treated injuries exhibited a more organized structure when compared to tendon defects that were repaired only with suturing or unseeded scaffolds. We suggest that iTenocyte-seeded DuRepair™ collagen scaffold can be used as potential treatment to regenerate the tendon tissue biomechanically and functionally.

Structural Characterization and Hydration Dynamics of Cross-Linked Collagen and Hyaluronic Acid Scaffolds by Nuclear Magnetic Resonance.

Understanding a biomaterial's structural and hydration dynamics is essential for its development and applications in tissue regeneration. In this study, collagen-hyaluronic acid (HA) scaffolds were analyzed utilizing Nuclear Magnetic Resonance (NMR) techniques to elucidate how different cross-linking conditions influence the internal architecture and interaction with solvents in these scaffolds. The scaffolds were fabricated using 3D printing and cross-linked with 1,4-butanediol diglycidyl ether (BDDGE), a process known to impact their mechanical properties. We gained insights into the microstructural organization and hydration behavior within the scaffolds when exposed to water and ethanol by employing proton relaxation and diffusion measurements. To better understand the system's performance, static and dynamic experiments were performed. Our results indicate that the degree of cross-linking affects the scaffold's ability to retain water, with higher cross-linking leading to more rigid structures. This also altered the hydration dynamics mainly due to a difference in the diffusion of water within the scaffold. In addition, the anisotropy of the collagen fibers also decreases with the cross-linking. Ethanol, a less polar solvent, provided a contrasting environment that further revealed the structural dependencies on the cross-linking density. The study's findings contribute to a deeper understanding of how the structure and morphology affect the functionality of collagen-HA scaffolds, offering critical information for optimizing their design for specific biomedical applications, such as soft tissue regeneration. Our experiments show how NMR is a valuable tool to provide information on dynamic processes not only in collagen-HA scaffolds but also in many biocompatible polymeric samples. The outcomes of this research provide a foundation for future work aimed at tailoring scaffold properties to enhance their performance in clinical settings, ultimately advancing the field of tissue engineering.

FRESH 3D Bioprinting of Collagen Types I, II, and III.

Collagens play a vital role in the mechanical integrity of tissues as well as in physical and chemical signaling throughout the body. As such, collagens are widely used biomaterials in tissue engineering; however, most 3D fabrication methods use only collagen type I and are restricted to simple cast or molded geometries that are not representative of native tissue. Freeform reversible embedding of suspended hydrogel (FRESH) 3D bioprinting has emerged as a method to fabricate complex 3D scaffolds from collagen I but has yet to be leveraged for other collagen isoforms. Here, we developed collagen type II, collagen type III, and combination bioinks for FRESH 3D bioprinting of millimeter-sized scaffolds with micrometer scale features with fidelity comparable to scaffolds fabricated with the established collagen I bioink. At the microscale, single filament extrusions were similar across all collagen bioinks with a nominal diameter of ∼100 μm using a 34-gauge needle. Scaffolds as large as 10 × 10 × 2 mm were also fabricated and showed similar overall resolution and fidelity across collagen bioinks. Finally, cell adhesion and growth on the different collagen bioinks as either cast or FRESH 3D bioprinted scaffolds were compared and found to support similar growth behaviors. In total, our results expand the range of collagen isoform bioinks that can be 3D bioprinted and demonstrate that collagen types I, II, III, and combinations thereof can all be FRESH printed with high fidelity and comparable biological response. This serves to expand the toolkit for the fabrication of tailored collagen scaffolds that can better recapitulate the extracellular matrix properties of specific tissue types.

Long-term Results of Lymphedema Treatment with combined Lymph Node Transfer and Collagen Scaffolds: An observational study

Aim: Vascularized lymph node transfer (VLNT) accelerates growth factor secretion, lymphatic endothelial-cell migration towards the interstitial flow and lymphagiogenesis in a multidirectional pattern. Our observational study aims to examine the hypothesis that nanofibrillar collagen scaffolds (NCS) combined with VLNT can provide guided lymphagiogenesis creating long-lasting lymphatic pathways.Methods: Twenty-four patients (21 female, 3 male) who had undergone a lymphatic microsurgery for upper (n=11) or lower (n=13) limb secondary lymphedema and completed at least 18months follow up were selected and equally divided in two groups; Group-A underwent a VLNT, Group-B a combined VLNT and NCS procedure. Lymph-node flap sizes, harvesting procedure and implantation location were resembling in both groups. Demographics, lymphedema etiology and staging, limb volumetry, and somatometric data were recorded. Pre- and postoperative data for limb-volume difference, infection episodes/year, and indocyanine-green (ICG) lymphography changes were documented in all patients.Results: Mean follow-up was 42 months24-60 in Group-A, and 27 months18-48 in Group-B patients. Demographic data, lymphedema etiology, and staging were comparable in both groups. Pre- and postoperative edema volume difference for Group-A was 36% and 25% (p<0.001), while in Group-B 33% and 14% (p=0.001) respectively. The mean number of infection episodes decreased in Group-A and B from 1.75 to 0.33 and from 2.17 to 0.42 per patient/year, respectively. ICG mean stage in Group-A was 3.58 pre- and 3 postoperatively (p=0.045), and 3.67 pre- and 2.08 postoperatively in Group-B (p=0.506). A statistically significant difference was found in postoperative volume difference between the two groups (p=0.008) as well as the postoperative ICG changes (p<0.001). ICG-lymphography demonstrated new lymphatic vessel formation at the location of NCS implantation.Conclusions: Long-term follow-up of the patients treated with a combined VLNT-NCS approach revealed a statistically significant improvement regarding volume reduction, infection episodes per year, ICG downstaging and new lymphatic vessel formation, compared to VLNT alone.

Incorporation of metal-doped silicate microparticles into collagen scaffolds combines chemical and architectural cues for endochondral bone healing.

Regeneration of large bone defects remains a clinical challenge until today. While existing biomaterials are predominantly addressing bone healing via direct, intramembranous ossification (IO), bone tissue formation via a cartilage phase, so-called endochondral ossification (EO) has been shown to be a promising alternative strategy. However, pure biomaterial approaches for EO induction are sparse and the knowledge how material components can have bioactive contribution to the required cartilage formation is limited. Here, we combined a previously developed purely architecture-driven biomaterial approach with the release of therapeutic metal ions from tailored silicate microparticles. The delivery platform was free of calcium phosphates (CaP) that are known to support IO but not EO and was employed for the release of lithium (Li), magnesium (Mg), strontium (Sr) or zinc (Zn) ions. We identified an ion-specific cellular response in which certain metal ions strongly enhanced cell recruitment into the material and showed superior chondrogenesis and deposition collagen II by human mesenchymal stromal cells (MSCs). At the same time, in some cases microparticle incorporation altered the mechanical properties of the biomaterial with consequences for cell-induced biomaterial contraction and scaffold wall deformation. Collectively, the results suggest that the incorporation of metal-doped silicate microparticles has the potential to further improve the bioactivity of architectured biomaterials for bone defect healing via EO. STATEMENT OF SIGNIFICANCE: Endochondral bone healing, a process that resembles embryonic skeletal development, has gained prominence in regenerative medicine. However, most therapeutic biomaterial strategies are not optimized for endochondral bone healing but instead target direct bone formation through IO. Here, we report on a novel approach to accelerate biomaterial-guided endochondral bone healing by combining cell-guiding collagen scaffolds with therapeutic metal-doped silicate microparticles. While other strategies, such as hypoxia-mimic drugs and iron-chelating biomaterials, have been documented in the literature before to enhance EO, our approach uniquely implements enhanced bioactivity into a previously developed biomaterial strategy for bone defect regeneration. Enhanced cell recruitment into the material and more pronounced chondrogenesis were observed for specific hybrid scaffold formulations, suggesting a high relevance of this new biomaterial for improved endochondral bone healing.

Predictive control of pore architecture in ice-templated scaffolds via heat flux density modulation

Replicating the intricate architecture of native tissues remains a significant challenge in tissue engineering. Ice-templated biomimetic scaffolds possess controlled porosity that conveniently resembles the native parenchyma of many tissues. In this study, we investigate the relationship between the porous architecture of lyophilised collagen scaffolds and key processing parameters during production. We establish a predictive model that correlates specific lyophilisation conditions with the resulting pore sizes. Systematic variations in the freeze-drying conditions resulted in scaffolds with average pore sizes ranging from 46 μm to 251 μm, effectively matching the length scale of extracellular matrix features found in native tissues. We introduce the concept of heat flux density (HFD) at equilibrium as a metric for quantifying latent heat extraction efficiency during the freezing process. Our findings reveal a power law relationship between HFD at equilibrium and pore size, with an exponent of −0.44. This approach provides a non-destructive and non-intrusive method for precisely controlling pore architecture, advancing the potential for creating scaffolds that closely emulate the complex structures of native tissues.

Biomimetic Mineralized Collagen Scaffolds for Bone Tissue Engineering: Strategies on Elaborate Fabrication for Bioactivity Improvement.

Biomimetic mineralized collagen (BMC) scaffolds represent an innovative class of bone-repair biomaterials inspired by the natural biomineralization process in bone tissue. Owing to their favorable biocompatibility and mechanical properties, BMC scaffolds have garnered significant attention in bone tissue engineering. However, most studies have overlooked the importance of bioactivity, resulting in collagen scaffolds with suboptimal osteogenic potential. In this review, the composition of the mineralized extracellular matrix (ECM) in bone tissue is discussed to provide guidance for biomimetic collagen mineralization. Subsequently, according to the detailed fabrication procedure of BMC scaffolds, the substances that can regulate both the fabrication process and biological activities is summarized. Furthermore, a potential strategy for developing BMC scaffolds with superior mechanical properties and biological activities for bone tissue engineering is proposed.

Dynamic-Cross-Linked, Regulated, and Controllable Mineralization Degree and Morphology of Collagen Biomineralization.

The cross-linking process of collagen is one of the more important ways to improve the mineralization ability of collagen. However, the regulatory effect of dynamic cross-linking on biomineralization in vitro remains unclear. Dynamic-cross-linked mineralized collagen under different cross-linking processes, according to the process of cross-linking and mineralization of natural bone, was prepared in this study. Mineralization was performed for 12 h at 4, 8, and 12 h of collagen cross-linking. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the characteristics of dynamic-cross-linked mineralization in terms of morphological transformation and distribution. Fourier transform infrared spectroscopy (FTIR) analysis showed the crystallinity characteristics of the hydroxyapatite (HA) crystal formation. Pre-cross-linked dynamic-cross-linked mineralization refers to the process of cross-linking for a period of time and then side cross-linked mineralization. The mineral content, enzyme stability, and mechanical properties of mineralized collagen were improved through a dynamic cross-linking process of pre-cross-linking. The swelling performance was reduced through the dynamic cross-linking process of pre-cross-linking. This study suggests that the dynamic cross-linking process through pre-cross-linking could make it easier for minerals to permeate and deposit between collagen fibers, improve mineralization efficiency, and, thus, enhance the mechanical strength of biomineralization. This study can provide new ideas and a theoretical basis for designing mineralized collagen scaffolds with better bone repair ability.

Biological and structural properties of curcumin-loaded graphene oxide incorporated collagen as composite scaffold for bone regeneration.

To address the challenges related to bone defects, including osteoinductivity deficiency and post-implantation infection risk, this study developed the collagen composite scaffolds (CUR-GO-COL) with multifunctionality by integrating the curcumin-loaded graphene oxide with collagen through a freeze-drying-cross-linking process. The morphological and structural characteristics of the composite scaffolds were analyzed, along with their physicochemical properties, including water absorption capacity, water retention rate, porosity, in vitro degradation, and curcumin release. To evaluate the biocompatibility, cell viability, proliferation, and adhesion capabilities of the composite scaffolds, as well as their osteogenic and antimicrobial properties, in vitro cell and bacterial assays were conducted. These assays were designed to assess the impact of the composite scaffolds on cell behavior and bacterial growth, thereby providing insights into their potential for promoting osteogenesis and inhibiting infection. The CUR-GO-COL composite scaffold with a CUR-GO concentration of 0.05% (w/v) exhibits optimal biological compatibility and stable and slow curcumin release rate. Furthermore, in vitro cell and bacterial tests demonstrated that the prepared CUR-GO-COL composite scaffolds enhance cell viability, proliferation and adhesion, and offer superior osteogenic and antimicrobial properties compared with the CUR-GO composite scaffold, confirming the osteogenesis promotion and antimicrobial effects. The introduction of CUR-GO into collagen scaffold creates a bone-friendly microenvironment, and offers a theoretical foundation for the design, investigation and utilization of multifunctional bone tissue biomaterials.

Human embryonic stem cell-derived immunity-and-matrix-regulatory cells on collagen scaffold effectively treat rat corneal alkali burn

Corneal alkali burns (CAB) are a severe form of ocular injury that often leads to significant vision loss, with limited effective treatment options available beyond corneal transplantation. Immunity and matrix-regulatory cells (IMRCs) have emerged as a promising alternative due to their ability to modulate immune responses and support tissue repair. This study investigates the efficacy of IMRCs on collagen scaffolds (IMRCs-col) for treating CAB in a rat model. We developed a novel treatment combining IMRCs with a collagen scaffold to align with the ocular surface structure. In vitro analyses showed that IMRCs-col significantly upregulated the expression of immune regulatory molecules, including IL-1RA and SCF. Additionally, IMRCs-col effectively inhibited the production of pro-inflammatory cytokines (IL-8 and Gro-a/CXCL1) while promoting pro-regenerative cytokines (bFGF, HGF, and PDGF). In an animal model of CAB, IMRCs-col transplantation demonstrated substantial efficacy in restoring corneal opacity and reducing neovascularization. Histological examination revealed reduced inflammation and improved corneal tissue regeneration compared to untreated CAB. Enhanced activation of pathways associated with anti-inflammatory responses and tissue repair was observed at days 3, 7, and 21 post-treatment.

Unraveling the role of integrating signal peptides into natural collagen on modulating cancer cell adhesion

The signal peptides GVMGFO and GFOGER exhibit differential binding affinities towards Michigan Cancer Foundation-7 (MCF-7) breast cancer cells and HT-1080 human fibrosarcoma cells, respectively, which in turn modulate the cell adhesion properties of natural collagen. GVMGFO demonstrates a more potent interaction with discoidin domain receptor 1(DDR1)-expressing MCF-7 cells, whereas GFOGER preferentially binds to the integrin α2β1 present on HT-1080 cells. The integration of GVMGFO into natural collagen through direct doping or crosslinking markedly enhances its association with MCF-7 cells, especially when optimal peptide concentrations and blending ratios are utilized, indicating a synergistic effect. This augmented adhesion is attributed to specific binding at the DDR1-collagen interface, facilitated by a constellation of amino acids within the collagen scaffold engaging with the DDR1 discoidin (DS) domain through polar interactions and hydrogen bonding. Conversely, the incorporation of GFOGER into natural collagen through co-assembling or crosslinking leads to a progressive increase in adherence to HT-1080 cells, as evidenced by the peptide's affinity for integrin α2β1. These findings advance the design of collagen-based biomaterials for targeted cellular interactions in the medical, pharmaceutical, and enhance our understanding of the molecular mechanisms governing peptide-collagen mediated cell adhesion processes.

Translational implications of a novel combination of iPRF and collagen scaffold for proliferation of gingival mesenchymal stem cells

“Tissue engineering,” is a concept that involves the use of scaffolds, cells, and growth factors/signaling molecules in the field of regenerative medicine. The present study was carried out to evaluate the attachment and depth of penetration of the Gingival Mesenchymal Stem Cells (GMSCs) onto the collagen scaffold preconditioned with Fetal Bovine Serum (FBS), Injectable Platelet Rich Fibrin (i-PRF) and a combination of FBS with i-PRF using histological analysis and environmental scanning electron microscopy (ESEM) respectively. In the present study, commercially available collagen membranes were used as scaffolds and divided into 3 groups where Group I was preconditioned with FBS, Group II was preconditioned with i-PRF, and Group III with a combination of FBS and i-PRF. Scaffolds were then seeded with GMSCs and incubated in a CO2 incubator at 37 0C for 7 days. Both histological and ESEM analysis showed proliferation, attachment, and depth of penetration along with the combination of cell morphological changes in all the three groups. In group I cells showed mild depth of penetration along with a round morphological appearance. In group II the cells showed moderate depth of penetration and rounded morphology. In group III maximum depth of penetration was seen along with the round and spheroidal morphology of cells. The combination of the growth media showed the best effect on cell attachment, depth of penetration, and cell morphology. This is the first report demonstrating the effect of the combination of collagen and i-PRF supports the proliferation of GMSCs. Since FBS alone and i-PRF alone exhibited similar cell proliferation it is recommended that i-PRF could be used in clinical scenarios making it xenofree.