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Made available in DSpace on 2022-04-28T17:30:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-28 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Introduction: Gingival recession (GR) is a relevant clinical condition due to its high prevalence worldwide, which leads to aesthetic demands and dentin hypersensitivity. Collagen matrices have been associated with different designs of coronally advanced flaps (CAFs) to treat GR defects. However, the literature lacks long-term follow-up of this treatment option. The aim of this study is to present the long-term follow-up (up to 7 years) of two GR defects (associated or not with noncarious cervical lesion) treated with a CAF and a collagen matrix (CM). Case presentation Case 1 underwent a CAF associated with a CM to treat a single GR defect. After 7 years, Case 1 presented with 3 mm of recession reduction, which corresponds with the 85.7% of root coverage. Case 2 presented two GR defects associated with noncarious cervical lesions (NCCLs). The NCCLs were partially restored with resin composite and then underwent a modified CAF for multiple defects and a CM. After 5 years of follow-up, Case 2 presented with 1.5 and 2.5 mm of recession reduction, which corresponds with the average 83.3% defect coverage. Conclusion These two cases may show that CMs can provide long-term stable outcomes in the treatment of GR defects. Fed Univ Pernambuco UFPE, Dept Prosthesis & Surg Orofacial, Recife, PE, Brazil Sao Paulo State Univ, Inst Sci & Technol, Div Periodont, UNESP, Av Engn Francisco Jose Longo 777, BR-12245000 Sao Jose Dos Campos, SP, Brazil Private Educ Inst, Sao Paulo, Brazil Sao Paulo State Univ, Inst Sci & Technol, Div Periodont, UNESP, Av Engn Francisco Jose Longo 777, BR-12245000 Sao Jose Dos Campos, SP, Brazil CAPES: 001 CNPq: 304269/2019-0

Synthetically sulfated hyaluronan derivatives were shown to facilitate osteogenic differentiation of human bone marrow stromal cells (hBMSC) by application in solution or incorporated in thin collagen-based coatings. In the presented study, using a biomimetic three-dimensional (3D) cell culture model based on fibrillary collagen I (3D Col matrix), we asked on the impact of binding mode of low sulfated hyaluronan (sHA) in terms of adsorptive and covalent binding on osteogenic differentiation of hBMSC. Both binding modes of sHA induced osteogenic differentiation. Although for adsorptive binding of sHA a strong intracellular uptake of sHA was observed, implicating an intracellular mode of action, covalent binding of sHA to the 3D matrix induced also intense osteoinductive effects pointing towards an extracellular mode of action of sHA in osteogenic differentiation. In summary, the results emphasize the relevance of fibrillary 3D Col matrices as a model to study hBMSC differentiation in vitro in a physiological-like environment and that sHA can display dose-dependent osteoinductive effects in dependence on presentation mode in cell culture scaffolds.

Microscale mechanical properties of the extracellular matrix (ECM) and dynamic cell-ECM interactions play an important role in pathophysiological processes, including the onset, progression, and attenuation of disease. The ability to quantitatively image cell-mediated micromechanical dynamics of the ECM in physiologically relevant 3D engineered cellular systems can significantly enhance the clinical translational potential of fundamental discoveries in the rapidly growing field of mechanobiology. However, it remains a challenge for current mechanical characterization methods to combine quantitative 3D imaging of ECM mechanics with cellular-scale resolution and dynamic monitoring of cell‑mediated changes to pericellular viscoelasticity. Here, we present light-sheet photonic force optical coherence elastography (LS-pfOCE) to address this challenge by leveraging a light-sheet for parallelized, non-invasive, and localized mechanical loading. We demonstrate the capabilities of LS-pfOCE by imaging the micromechanical heterogeneity of fibrous 3D collagen matrices and perform a live-cell study to image micromechanical heterogeneity induced by NIH-3T3 cells seeded in 3D fibrin constructs. We also show that LS-pfOCE is able to quantify temporal variations in pericellular viscoelasticity in response to drug-induced altered cellular activity. By providing access to 4D spatiotemporal variations in the micromechanical properties of 3D biopolymer constructs and engineered cellular systems, LS‑pfOCE has the potential to drive new discoveries in mechanobiology and contribute to the development of novel biomechanics-based clinical diagnostics and therapies.

Wounds take the main places of among surgical diseases, and the problem of developing new methods of their treatment remains relevant today. In recent years, the use of collagen has been widely used in the treatment of wounds. Collagen modulates the flow of fluid from the wound, facilitates the migration of fibroblasts and the formation of microvessels, helps in the synthesis of neodermal collagen matrices, forms complexes with biologically active substances and minimizes the formation of scars.Currently, collagen is used in the treatment of soft tissue wounds in the form of several pharmaceutical forms. Collagen sponges are used in the treatment of thermal and mechanical wounds, for local delivery of medicines. Collagen gels can be used for injections. Collagen can also be implemented in the form of a collagen shield. There are also collagen granules that have been developed for various compounds.Thus, the use of collagen is promising in the development of new medicinal preparation. However, for a wider disclosure of its clinical potential, it is necessary to thoroughly study all types of collagen and reveal their role at different stages of soft tissue repair.

Purpose: The purpose of the study was to evaluate the ability of periostin when impregnated onto varied collagen matrices to influence osteoblast cell adhesion, proliferation, and activity. Materials and Methods: Saos-2 osteoblast cells were cultured and seeded onto two different collagen matrices as follows: Group A: absorbable collagen sponge (ACS), Group B: ACS impregnated with recombinant human periostin, Group C: nanocrystalline hydroxyapatite collagen (NcHC), and Group D: NcHC impregnated with recombinanant human periostin. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed to evaluate cell viability as well as adhesion and proliferation on 2nd, 5th, and 7th day. Osteoblast activity was studied using alkaline phosphatase (ALP) assay for the study groups. Results: The periostin-treated absorbable collagen matrices showed a statistically significant increase in the osteoblast adhesion compared to periostin-treated NcHC on days 2, 5, and 7 (P < 0.001). The osteoblast activity as evaluated by ALP assay showed that there is increased activity in the periostin-treated ACS compared to the periostin-treated NcHC. Conclusion: From the observations of this study, it is evident that Periostin has a significant role in the modulating cellular response of the osteoblast cells. Further, incorporation of periostin into the ACS has been shown to increase the cell viability, proliferation, and adhesion of osteoblast-like Saos-2 cells.

Relevance. The development of safe and effective methods and medical products for augmentation of soft tissues in the oral cavity has been the basis for research in experimental and clinical dentistry for more than a year. The widespread use of materials for restoring the volume of soft tissues in surgical dentistry is mainly due to the requirement of patients for aesthetics in visually significant areas of the oral cavity. At the moment, the medical market offers a large number of scaffolds for the restoration of defects in the maxillofacial region, which in turn are made from biological and synthetic raw materials. Collagen matrices occupy an important place among scaffolds. Compared to commonly used inert matrices, the advantages of using combined tissue-engineering constructs with biologically active ingredients have been demonstrated. Associated with this is the growing popularity of implantable medical devices based on the use of extracellular collagen matrix. The extracellular collagen matrix serves as the basis for the growth of cell culture and is an independent matrix that transforms into healthy recipient tissue. Purpose . An experimentally-clinical research of functional action of collagen matrix in experiment in vivo on animals. Materials and methods . The study was conducted in the vivarium of the experimental station of the all-Russian research Institute of sheep and goat breeding. Four Mature sheep of the North Caucasian meat-wool breed aged 1.5 to 2 years were used in the in vivo experiment. The body weight of the animals was 35-40 kg. Sheeps were divided into two groups of two individuals. The first group of animals was excluded 3 months after the implantation of collagen matrix samples, the second group was excluded after 6 months. At experiments statement the principle of “divided mouth" was used, where right half of the jaw was of control, and left-hand experienced. After taking the materials from the animals, the degree of biointegration, biodegradation of the samples and vascularization of the newly formed connective tissue in the area of collagen matrix implantation were analyzed. Results. According to the results of microscopic examination of samples of connective tissue of the inflammatory process was not revealed. Connective tissue in all samples is represented by decorated and unformed connective tissue, a large number of fibrocytes and fibroblasts were found. Conclusion. The results showed that for soft tissue volume augmentation of the oral mucosa it is effective and safe to use samples from veal, pork collagen and dura mater. Also, experimental samples of collagen matrix showed the same results of biointegration, biodegradation and vascularization as the control ones.

Cancer metastasis involves not only cancer cells but also fibroblasts and the surrounding collagen matrices. Previous studies have reported that in tumor tissues, cancer cells and fibroblasts surrounded by dense collagen are often associated with a high risk of cancer metastasis. However, the mechanism of the interaction between the cancer cells, fibroblasts, and the surrounding collagen matrices

The quality and quantity of peri-implant soft tissues at the crestal portion of dental implants are important aspects to consider for a long-term successful implant-supported rehabilitation. Some relevant factors attributed to the implant health include mucosal thickness and keratinization. In this respect, many techniques and materials have been described to augment and improve buccal peri-implant soft tissues. Over the last few years, newly developed xenogeneic collagen matrices have been introduced in peri-implant plastic surgery to replace autogenous soft tissue grafts; however, data remain controversial so far. Thus, the purpose of the present report was to present a novel surgical technique conceived to augment buccal peri-implant soft tissues in combination with a volume-stable porcine collagen matrix. The rationale and the fundamental concepts that led to the use of a xenogeneic matrix to increase soft tissue volumes were also discussed.

Soft gingival tissue deficiency remains a severe problem leading to postoperative recession, peri-implantitis, and bone resorption. The use of collagen matrices does not always lead to complete rebuilding of the gingiva volume. The application of mesenchymal stromal cells (MSCs) simultaneously with collagen materials represents a promising approach for the restoration of soft gingival tissues. However, short-term effects of MSCs-enriched collagen grafts after gingival augmentation have not yet been studied properly. Mucograft and Mucoderm matrices were implanted in rabbits (n = 12) simultaneously with the intraoperative injection of rabbit bone marrow-derived mesenchymal stromal cells (BM-MSCs) or without cells. Collagen matrices were implanted under the flap or by the surface technique without intentional primary closure. The samples were harvested seven days after implantation, histological staining with hematoxylin and eosin, and immunohistochemical staining for VEGF, IGF1, and TGF were performed. The use of Mucoderm led to better augmentation outcomes on day 7 compared with Mucograft (p &lt, 0.0001). Gingival augmentation in combination with the local administration of BM-MSCs led to better regeneration of the soft gingival tissues independently of the type of implanted collagen matrices (p &lt, 0.0001). Furthermore, injection of BM-MSCs significantly enhanced gingival vascularization and epithelization with a clear positive correlation between vascular growth and epithelial response. Administration of BM-MSCs in combination with various collagen materials may potentially improve gingiva regeneration.

The cross-linking of collagen matrices (Cl_CM) may provide volume-stable enhanced defect regeneration when compared to non-cross-linked matrices (Ncl_CM). The aim of the present study was to investigate the bone forming potential of collagen matrices (CMs) and the effects of cross-linking CMs in a rabbit calvaria defect model. (1) Empty controls (n = 6), (2) Ncl_CM (n = 8), and (3) Cl_CM (n = 8) were selected to be observed for the healing in 10 mm critical-sized calvarial bone defects. The potential for the bone as well as the connective tissue formation were evaluated by micro-CT and histomorphometry at three months post-surgery. There were no statistically significant differences in terms of new bone volume in the defects between the groups. However, the Cl_CM induced significantly greater fibrous tissue regeneration (5.29 ± 1.57 mm2) when compared to the controls (3.51 ± 0.93 mm2) by histomorphometry. The remnants of collagen fibers with immune cells, including macrophages and giant cells, were occasionally observed in the Cl_CM group but not in the Ncl_CM group. In conclusion, the cross-linking of collagen did not influence the potential for bone formation. Nevertheless, Cl_CM might be advantageous for the maintenance of fibrous tissue volume without disturbing bone formation in the defects.

Collagen and collagen-based materials have been successfully used in medicine for over 50 years. The number of scientific articles about the role of collagen in the construction of scaffolds for tissue engineering has risen precipitously in recent years. The review contains materials about historic and modern applications of collagen in medicine such as soluble collagen injections, solid constructs reconstructed from solution, and decellularized collagen matrices. The analysis of published data proves the efficacy of collagen material in the treatment of chronic wounds, burns, venous and diabetic ulcers, in plastic, reconstructive and general surgery, urology, proctology, gynecology, ophthalmology, otolaryngology, neurosurgery, dentistry, cardiovascular and bone and cartilage surgery, as well as in cosmetology. Further development of collagenoplasty requires addressing the problems of allergic complications, improvement of structure and maximizing therapeutic effects against pathological processes.

This work was supported by: (1) the Ministry of Economy and Competitiveness and European Regional Development Fund [Project MAT2017-85999-P MINECO/AEI/FEDER/UE], (2) University of Granada/Regional Government of Andalusia Research Fund from Spain and European Regional Development Fund (A-BIO-157-UGR-18/FEDER). This research is part of C.V.'s PhD research study., Soft tissues have been shown to be critical for the maintenance of both teeth and implants. Currently, regenerative soft tissue techniques propose the use of collagen matrices, which can avoid the drawbacks derived from the obtainment of autogenous tissue graft. A systematic review and meta-analysis were conducted to ascertain the efficacy of collagen matrices (CM) compared to autogenous connective tissue graft (CTG) to improve soft tissue dimensions. An electronic and manual literature searches were performed to identify randomized clinical trials (RCT) or controlled clinical trials (CCT) that compared CTG and CM. Pooled data of width of keratinized tissue (KT) and mucosal thickness (MT) were collected and weighted means were calculated. Heterogeneity was determined using Higgins (I-2). If I-2 > 50% a random-effects model was applied. Nineteen studies were included based on the eligibility criteria. When using CTG a higher MT gain (0.32 mm, ranging from 0.49 to 0.16 mm) was obtained than when employing CM. Similar result was obtained for the width of KT gain, that was 0.46 mm higher (ranging from 0.89 to 0.02 mm) when employing CTG. However, it can be stated that, although autogenous CTG achieves higher values, CM are an effective alternative in terms of total width of KT and MT gain., Ministry of Economy and Competitiveness MAT2017-85999-P MINECO/AEI/FEDER/UE, European Commission MAT2017-85999-P MINECO/AEI/FEDER/UE A-BIO-157-UGR-18/FEDER, University of Granada/Regional Government of Andalusia Research Fund from Spain

Haemostatic materials such as: gelatine sponges, oxygenated cellulose meshes, tissue sealants, collagen matrices with human thrombin and fibrinogen are gaining on popularity in gastrointestinal surgery, especially in colorectal surgery. We searched for available scientific publications in the Pubmed and Cochrane database on the use of individual hemostatic materials in the field of gastrointestinal surgery. The analysis focused on the assessment of the safety of the use of individual materials in terms of the rate of bleeding complications and the rate of anastomotic leakage cases. The use of haemostatic materials has for years been a recognized method of reducing the rate of intra- and postoperative complications, both in gastrointestinal surgery and in other surgical specialties. Based on the available studies, it can be concluded that the use of hemostatic materials such as matrices, sponges and adhesives in gastrointestinal surgery, even in patients at high risk of anastomotic leakage and bleeding complications, reduces the incidence of complications. The growing popularity of haemostatics and sealants in surgery means that they are currently used in a wide range of indications, and surgeons are more and more willing to use them even in case of standard surgical procedures, which is reflected in the available studies. Choosing a haemostat should be a conscious decision, taking into account the site and type of bleeding, mechanism of action, ease of use, efficacy, safety, and price, among others.

Peri-implant keratinized mucosa (PI-KM) may support implant survival. Acellular collagen matrices (aCMs) have been widely used to facilitate soft tissue regeneration. The aim of this study was to investigate clinical outcomes obtained with the use of an aCM (mucoderm®) to enhance PI-KM. In this retrospective non-randomized case series, 27 restored implants in 14 patients (eight males and six females, mean age = 56 years) with a PI-KM width ≤ 1 mm were followed for 6 months. It was demonstrated that aCM grafts augmented PI-KM effectively (mean increase of 5.4 mm, &gt, 533%) without a significant change in bleeding on probing (BOP) from baseline. The mean aCM shrinkage was 3.9 mm (42%). Gender, area, arch, and BOP did not influence PI-KM augmentation or aCM shrinkage significantly. The present results demonstrated that the examined aCM was effective and predictable for attaining a band of keratinized tissue, while avoiding graft donor site harversting.

The tunability of collagen at a fibrillar and molecular level, along with its proteolytic degradability, can offer a great potential to create multifunctional soft tissue grafts capable of spatiotemporal molecular delivery. However, conventional collagen implants with minimal or no crosslinking provide little control over tunability without having exogenously cross-linked and/or chemically treated. Without these modifications, conventional collagen formulations degrade rapidly, without allowing for the host tissue to deposit its own ECM (Liang HC, Chang Y, Hsu CK, Lee MH, Sung HW, Biomaterials 25:3541–3552, 2004). Therefore, there is a need to regulate collagen microstructure as well as the degradation (Perez-Puyana V, Romero A, Guerrero A, J Biomed Mater Res Part A 104:1462–1468, 2016) in a way that preserves collagen properties and provides desired molecular release kinetics. When designing a drug delivery system, it is important to quantify molecular release kinetics, analyze the empirical model of molecular release, and elucidate the mechanisms involved in the release process (Siegel RA, Rathbone MJ, Fundamentals and applications of controlled release drug delivery. Springer US, Boston, 2012).

Porcine acellular dermal matrix has recently been introduced in dentistry as an alternative to the gold standard connective tissue graft especially for the use in gingival recession treatments and soft tissue augmentation in implant surgery. Connective tissue grafts are inconvenient and require a second surgical site leading to greater morbidity, longer surgical procedures, and a more painful postoperative phase for the patient. Other options such as allografts have ethical concerns and are less available in Europe. Thus, dental professionals have sought other techniques and materials. Porcine acellular dermal matrix results in periodontal recession treatment with a gain in recession coverage as well as increased keratinized tissue and soft tissue augmentation. This leads to more keratinized mucosa and greater tissue thickness. Many studies have been published using collagen matrices, but a few strictly use porcine acellular dermal matrix, which have been studied in prospective randomized clinical trials with a large number of patients and longer follow-up periods (more than 5 years). Nevertheless, more data are needed to confirm that the porcine acellular dermal matrix is a suitable alternative although its favourable results to date suggest a positive future.

Modern biomedical science is challenged to develop new wound healing drugs. The collagen-containing wastes of leather industry could be the rich source of collagen products for further use in biomedical science. The aim of this research was to find the best source of collagen between limed pelt, delimed pelt and fleshings of cattle hides, and to prepare it for the use as a matrix for further microbiological studies. Collagen was extracted with 0.5 M acetic acid and 5 mM EDTA. The purity of the extracted collagen was checked by gel-electophoresis (SDS-PAGE). The rate of growth and crystal violet assay of laboratory strains (S. aureus, P. aeruginosa) were used for microbiological evaluation of obtained collagen matrices. The delimed pelt provided the highest concentration of collagen and the greatest volume of collagen products. All obtained collagen products were applicable as matrices for microbial cells growth. The applicability of collagen products from leather industry wastes for biomedical studies in Ukraine was shown.

Collagen is the most abundant protein in mammals, accounting for approximately one-third of the total protein in the human body. Thus, it is a logical choice for the creation of biomimetic environments, and there is a long history of using collagen matrices for various tissue engineering applications. However, from a biomaterial perspective, the use of collagen-only scaffolds is associated with many challenges. Namely, the mechanical properties of collagen matrices can be difficult to tune across a wide range of values, and collagen itself is not highly amenable to direct chemical modification without affecting its architecture or bioactivity. Thus, many approaches have been pursued to design scaffold environments that display critical features of collagen but enable improved tunability of physical and biological characteristics. This paper provides a brief overview of approaches that have been employed to create such engineered collagen matrices. Specifically, these approaches include blending of collagen with other natural or synthetic polymers, chemical modifications of denatured collagen, de novo creation of collagen-mimetic chains, and reductionist methods to incorporate collagen moieties into other materials. These advancements in the creation of tunable, engineered collagen matrices will continue to enable the interrogation of novel and increasingly complex biological questions.

Resorbable and volume-stable collagen matrices have been preferred as grafting materials for diverse clinical applications in recent years. On the other hand, there is always an existing risk of transmission of infection with the cells or the tissues of the graft in using such collagen matrices. Moreover, considering the economic aspects, there is also a need for cost-efficient alternative materials. In this sense, marine algae can be considered as alternatives since they represent vast and cheap source of potential biopolymers. This work covers a comprehensive cytocompatibility study of composite biopolymers derived from different types of marine algae. (C) 2020 Elsevier Ltd. All rights reserved.

Xenogeneic acellular collagen matrices represent a safe alternative to autologous soft tissue transplants in periodontology and implant dentistry. Here, we aimed to investigate the adsorption and release of growth factors from four porcine-derived collagen matrices using enzyme-linked immunosorbent assay. Non-crosslinked collagen matrix (NCM), crosslinked collagen matrix (CCM), dried acellular dermal matrix (DADM), and hydrated acellular dermal matrix (HADM) adsorbed each of the following growth factors, TGF-&beta, 1, FGF-2, PDGF-BB, GDF-5 and BMP-2, with an efficiency close to 100%. Growth factor release for a 13-day period was in the range of 10&ndash, 50% of the adsorbed protein, except for the BMP-2 release that was in the range of 5&ndash, 7%. Generally, protein release occurred in two phases. Phase I was arbitrary defined by the highest release from the matrices, usually within 24 h. Phase II, spanning the period immediately after the peak release until day 13, corresponded to the delayed release of the growth factors from the deeper layers of the matrices. HADM showed significantly (P &lt, 0.001) higher TGF-&beta, 1, FGF-2, and PDGF-BB release in phase II, compared to the rest of the matrices. NCM exhibited significantly (P &lt, 0.001) higher FGF-2 release in phase II, compared to CCM and DADM as well as a characteristic second peak in PDGF-BB release towards the middle of the tested period. In contrast to NCM and HADM, CCM and DADM showed a gradual and significantly higher release of GDF-5 in the second phase. Several burst releases of BMP-2 were characteristic for all matrices. The efficient adsorption and sustained protein release in the first 13 days, and the kinetics seen for HADM, with a burst release within hours and high amount of released growth factor within a secondary phase, may be beneficial for the long-term tissue regeneration following reconstructive periodontal surgery.

OBJECTIVES To evaluate the histologic and volumetric changes of gingival tissues following grafting with collagen-based matrices at labial aspect of teeth in canines. MATERIALS AND METHODS Gingival augmentation was performed in the mandibular incisor area using two types of xenogeneic cross-linked collagen matrices (CCMs), bovine CCM for BCCM group and porcine CCM for PCCM group, whereas the contralateral sides remained untreated (B-control group and P-control group). Descriptive histology, histometric and volumetric analyses were performed after 12 weeks. For statistical comparison between each test group and respective control group, paired t test was used for histometric analysis, and repeated-measured analysis of variance was used for volumetric analysis (p < 0.05). RESULTS An increased number of rete pegs and an enhanced formation of new blood vessels were observed at both grafted sites compared to the corresponding control sites. There was statistically significant gain of horizontal thickness only in BCCM group (1.36 ± 0.27 mm vs. 1.26 ± 0.34 mm; p < 0.05) compared to the B-control groups. CONCLUSION BCCM was effective for gingival augmentation in terms of horizontal thickness at the labial aspect of teeth at 12 weeks post-surgery.

Collagen matrices are one form of artificial tissue that has applications in biomimetic organs or tumors, and in fundamental biology. Anatomical organs and tissues are often composed of aligned collagen, and in this study cross-linking nickel magnetic nanowires (MNWs) to collagen allowed a one-step bi-directional alignment of the collagen matrices when processed in a uniform magnetic field. These matrices were analyzed by differential interference contrast (DIC) microscopy, scanning electron microscopy (SEM) and polarized transmittance. The bi-directional alignment was also confirmed by plated, stained arachnoid cells from the blood-brain-barrier (BBB). Arachnoid cells are morphologically sensitive to their extracellular matrix (ECM) environment, and in this study, they were observed to spider out in two distinct directions as predicted by microscopy and transmittance. In fact, MNW-collagen matrices plated with arachnoid-cells are promising for future studies of artificial BBBs. Other cells (here osteosarcoma) have been observed to internalize MNWs, which leads to the possibility of barcoding matrices and cells with distinct signatures, pending a magnetic readout technique. To this aim, mixtures of two different MNW populations were analyzed using first order reversal curves (FORC), and the relative concentrations of the two populations were correctly estimated with negligible error for ratios of 1: 23 and only 7% error for ratios of 1: 115. Together, these studies open a path for magnetic identification of artificial tissues where distinct magnetic labels on matrices and in cells combine for a unique fingerprint.

We previously reported that fibroblasts migrating within 3-D collagen matrices move independently, whereas fibroblasts within 3-D fibrin matrices form an interconnected network. Similar networks have been identified previously during in vivo corneal wound healing. In this study, we investigate the role of fibronectin in mediating this mechanism of collective cell spreading, migration and patterning.To assess cell spreading, corneal fibroblasts were plated within fibrillar collagen or fibrin matrices. To assess migration, compacted cell-populated collagen matrices were nested inside cell-free fibrin matrices. Constructs were cultured in serum-free media containing PDGF, with or without RGD peptide, anti-α5 or anti-fibronectin blocking antibodies. In some experiments, LifeAct and fluorescent fibronectin were used to allow dynamic assessment of cell-induced fibronectin reorganization. 3-D and 4-D imaging were used to assess cell mechanical behavior, connectivity, F-actin, α5 integrin and fibronectin organization.Corneal fibroblasts within 3-D fibrin matrices formed an interconnected network that was lined with cell-secreted fibronectin. Live cell imaging demonstrated that fibronectin tracks were formed at the leading edge of spreading and migrating cells. Furthermore, fibroblasts preferentially migrated through fibronectin tracks laid down by other cells. Interfering with cell-fibronectin binding with RGD, anti α5 integrin or anti fibronectin antibodies inhibited cell spreading and migration through fibrin, but did not affect cell behavior in collagen.In this study, a novel mode of cell patterning was identified in which corneal fibroblasts secrete and attach to fibronectin via α5β1 integrin to facilitate spreading and migration within 3-D fibrin matrices, resulting in the formation of localized fibronectin tracks. Other cells use these fibronectin tracks as conduits, resulting in an interconnected cell-fibronectin network.

The aim of this study were characterize acellular collagen matrices derived from porcine pericardium (PP) and to evaluate their properties after sterilization by ethylene oxide and gamma ray. PP matrices were subjected to alkaline hydrolysis (AH), and samples were characterized for biological stability, membrane thickness measurements, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Subsequently, the matrices were frozen, lyophilized and sterilized by ethylene oxide or gamma radiation. For in vitro assays, CHO-K1 cell culture was used and evaluated for cytotoxicity, clonogenic survival assay, genotoxicity and mutagenicity. Analysis of variance (ANOVA) was used, followed by Dunnett’s post-test, with a significance level of 5%. After AH, there was no significant change in matrix thickness. The relative biodegradability of the material after implantation was observed. Morphology and dimensions had small changes after AH. As for cell viability, none of the tested matrices showed a statistically significant difference (p &gt, 0.05, Dunnett) regardless of the sterilization method. Furthermore, it was found that PP matrices did not interfere with the proliferation capacity of CHO-K1 cells (p &gt, Dunnett). As for genotoxicity, when sterilized with ethylene oxide (NP, P12 and P24), it showed genotoxic potential, but it was not genotoxic when sterilized by gamma radiation. No mutagenic effects were observed in either group. PP-derived collagen matrices hydrolyzed at different times were not cytotoxic. It is concluded that the best method of sterilization is through gamma radiation, since no significant changes were observed in the properties of the PP matrices.

An article in the Proceedings of the National Academy of Sciences USA reports the engineering of lymphatic vessels in collagen matrices.

This work was supported by: (1) the Ministry of Economy and Competitiveness and the European Regional Development Fund (Project PID2020-114694RB-100 MINECO/AEI/FEDER/UE), (2) the University of Granada/Regional Government of Andalusia Research Fund from Spain, and the European Regional Development Fund (A-BIO-157-UGR-18/FEDER). This research is part of C.V.'s PhD research study., Collagen matrices have become a great alternative to the use of connective tissue grafts for soft tissue augmentation procedures. One of the main problems with these matrices is their volume instability and rapid degradation. This study has been designed with the objective of examining the degradation of three matrices over time. For this purpose, pieces of 10 10 mm2 of Fibro-Gide, Mucograft and Mucoderm were submitted to three different degradation tests— (1) hydrolytic degradation in phosphate buffer solution (PBS); (2) enzyme resistance, using a 0.25% porcine trypsin solution; and (3) bacterial collagenase resistance (Clostridium histolyticum)—over different immersion periods of up to 50 days. Weight measurements were performed with an analytic microbalance. Thickness was measured with a digital caliper. A stereomicroscope was used to obtain the matrices’ images. ANOVA and Student–Newman–Keuls tests were used for mean comparisons (p < 0.05), except when analyzing differences between time-points within the same matrix and solution, where pair-wise comparisons were applied (p < 0.001). Fibro-Gide attained the highest resistance to all degradation challenges. The bacterial collagenase solution was shown to constitute the most aggressive test as all matrices presented 100% degradation before 14 days of storage., Ministry of Economy and Competitiveness, European Commission PID2020-114694RB-100 A-BIO-157-UGR-18/FEDER, University of Granada/Regional Government of Andalusia Research Fund from Spain

Collagen is the primary protein component in mammalian connective tissues. Over the last 20 years, evidence has mounted that collagen matrices exhibit substantial heterogeneity in their hierarchical structures and that this heterogeneity plays important roles in both structure and function. Herein, an overview of studies addressing the nanoscale compositional and structural heterogeneity is provided and connected to work exploring the mechanical implications for a number of tissues.

The objective of this study was to test whether or not soft tissue augmentation with a volume-stable collagen matrix (VCMX) leads to similar volume gain around dental implants compared to autogenous subepithelial connective tissue graft (SCTG). In 12 adult beagle dogs, immediate implants were placed with simultaneous guided bone regeneration. After 25–45 weeks, soft tissue augmentation was randomly performed using VCMX, SCTG, or a sham-operated control. Impressions were taken pre-op and post-op (tissue augmentation) and again at sacrifice after healing periods of 4, 8, and 24 weeks. They were then digitized to allow for superimposition. Values of linear and volumetric changes were calculated. The median increase (pre-op to post-op) in buccal volume measured 0.92 mm for VCMX, 1.47 mm for SCTG, and 0.24 mm for SH. The values (pre-op to sacrifice) were − 0.25 mm for VCMX, 0.52 mm for SCTG, and − 0.06 mm for group SH. The median ridge width 2 mm below the crest measured − 0.26 mm for VCMX, 0.53 mm for SCTG, and − 0.15 mm for SH (pre-op to sacrifice). Volume augmentation using VCMX and SCTG resulted in an increase in ridge dimension (pre- to post-op). During the follow-up, the volume decreased in all three groups to a level close to the situation prior to surgery. Soft tissue volume augmentation around dental implants is usually performed using the patient’s own tissue. This therapy is associated with an increased morbidity due to a second surgical site. Soft tissue volume at implant sites can be augmented using VCMX and SCTG. The gain on top of the ridge appears not to be stable during the follow-up in both groups.