Copper-based dressing: Efficacy in a wound infection of ex vivo human skin

This study aimed to evaluate the wound healing and antibacterial effects of two experimental copper dressings compared to a commercial silver dressing. Burn wounds were created in the ex vivo human skin biopsies, then were infected by Staphylococcus aureus. Tissues were treated with copper dressings, silver dressing, or a dressing without any antibacterial component. An infected wound tissue without treatment was considered as the control group. Three days after treatments, tissues were analyzed by bacterial count and histology staining, while their media was used to assess the expression of cytokines and chemokines. Histology staining confirmed the presence of second-degree burn wounds and colonization of bacteria in the surface and superficial layer of tissues. The results demonstrated a higher antibacterial effect, improved epithelium formation, and decreased wound area in one of the copper dressings compared to other dressings. Markers associated with infection control increased in both the copper and silver-treated groups. The cytokine profiling analysis revealed increased expression of markers related to angiogenesis and anti-inflammatory responses and decreased pro-inflammatory cytokine responses in the infected wound treated with one of the copper dressings. Our results confirmed the efficacy of the experimental copper dressing in reducing bacteria and promoting wound healing.

Development of fibroblast/endothelial cell-seeded collagen scaffolds for in vitro prevascularization

The development of vascularized scaffolds remains one of the major challenges in tissue engineering, and co-culturing with endothelial cells is known as one of the possible approaches for this purpose. In this approach, optimization of cell culture conditions, scaffolds, and fabrication techniques is needed to develop tissue equivalents that will enable in vitro formation of a capillary network. Prevascularized equivalents will be more physiologically comparable to the native tissues and potentially prevent insufficient vascularization after implantation. This study aimed to culture human umbilical vein endothelial cells (HUVECs), alone or in co-culture with fibroblasts, on collagen scaffolds prepared by simple fabrication approaches for in vitro prevascularization. Different concentrations and ratios of HUVECs and fibroblasts seeded on collagen gel and sponge scaffolds under several culture conditions were examined. Cell viability, scaffolds morphology, and structure were analyzed. Collagen gel scaffolds showed good cell proliferation and viability, with higher proliferation rates for cells cultured in a 2:1 (fibroblasts: HUVECs) ratio and kept in endothelial cell growth medium. However, these matrices were unable to support endothelial cell sprouting. Collagen sponges were highly porous and showed good cell viability. However, they became fragile over time in culture, and they still lack signs of vascularization. Collagen scaffolds were a good platform for cell growth and viability. However, under the experimental conditions of this study, the HUVEC/fibroblast-seeded scaffolds were not suitable platforms to generate in vitro prevascularized equivalents. Our findings will be a valuable starting point to optimize culture microenvironments and scaffolds during fabrication of prevascularized scaffolds.

Coating of 3D printed PCL/TCP scaffolds using homogenized-fibrillated collagen

BACKGROUND

Poly(3-caprolactone) (PCL)/β-tricalcium phosphate (β-TCP) composite scaffolds fabricated by three-dimensional (3D) printing are one of the common scaffolds for bone tissue regeneration. However, the main challenge of these 3D printed PCL/β-TCP scaffolds is the fact that many cells pass from porosities during in vitro cell seeding, leading to poor initial cell attachment. This study aimed to demonstrate the fabrication of a new collagen coating process for optimizing the hydrophilic property and cell-substrate interactions. This method may be used for coating collagen on any relevant biomedical constructs made of synthetic polymers to increase their biocompatibility and cell attachment.

MATERIALS AND METHODS

Porous composite scaffolds fabricated by 3D printing were coated with collagen by a novel method and compared to traditional methods. After plasma treatment, samples were inverted in a homogenized collagen solution, freeze-dried, stabilized by crosslinking, freeze-dried again, and fibrillated using a defined salt concentration. Samples were characterized by a 3D laser microscope, cytocompatibility assay, attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy, water absorption, protein absorption, and bioactivity assay.

RESULTS

Homogenized collagen at pH= 7 resulted in a very uniform layer on the surface of scaffolds with significantly higher cell proliferation (p < 0.05). Collagen-coated scaffolds showed significantly higher water absorption, protein absorption, and bioactivity compared to non-coated samples (p < 0.05).

CONCLUSION

The results demonstrate that both the pH and collagen structure influence the coating of scaffolds, while the concentrations used in this study do not have a significant difference in this aspect. The combination of homogenization and fibrillization makes scaffolds more biocompatible and desirable for bone tissue engineering.

Exploring the millimetre emission in nearby galaxies: Analysis of the edge-on galaxy NGC 891

New observations of the edge-on galaxy NGC 891, at 1.15 and 2mm obtained with the IRAM 30-m telescope and the NIKA2 camera, within the framework of the IMEGIN (Interpreting the Millimetre Emission of Galaxies with IRAM and NIKA2) Large Program, are presented in this work. By using multiwavelength maps (from the mid-IR to the cm wavelengths) we perform SED fitting in order to extract the physical properties of the galaxy on both global and local (~kpc) scales. For the interpretation of the observations we make use of a state-of-the-art SED fitting code, HerBIE (HiERarchical Bayesian Inference for dust Emission). The observations indicate a galaxy morphology, at mm wavelengths, similar to that of the cold dust emission traced by submm observations and to that of the molecular gas. The contribution of the radio emission at the NIKA2 bands is very small (negligible at 1.15 mm and ~ 10% at 2 mm) while it dominates the total energy budget at longer wavelengths (beyond 5 mm). On local scales, the distribution of the free-free emission resembles that of the dust thermal emission while the distribution of the synchrotron emission shows a deficiency along the major axis of the disc of the galaxy.

Osteo-mucosal engineered construct: In situ adhesion of hard-soft tissues

OBJECTIVES

The aim of this work was to combine engineered hard and soft tissue, adopting a new method for interfacial adhesion of osteo-mucosal construct. We hypothesized that the chemical procedure involved in this method not only adheres the components, but also improves the cell growth inside them.

METHODS

3D-printed functionally-graded porous hard-tissue scaffolds were characterized, functionalized by aminolysis and tyrosinase, and accommodated by human osteoblast cells. Introducing amino groups through aminolysis and inducing dopaquinones by tyrosinase can take part in the Michael additions to cause the adhesion. Subsequently, fully-differentiated engineered oral mucosa was formed directly on the surface of hard tissue. Constructs were assessed in term of morphology, structure, chemical composition, histology, and cytocompatibility. Interfacial adhesion was compared to a control group prepared by using a biological glue for the attachment of the soft and hard tissues.

RESULTS

The data confirmed higher proliferation of osteoblast cells via aminolysis and improved osteoblast cells distribution and differentiation by incorporation of tyrosinase in collagen. There was evidence of multilayered, stratified epithelium on the osteo-mucosal model with viable fibroblasts and osteoblasts within the lamina propria and bone tissue layers. Our method of adhesion resulted in cohesive debonding within the engineered soft tissue; while in the control group, adhesive debonding and complete separation of the oral mucosa from the hard tissue was observed. Although the shear strength of the osteo-mucosal model (157.6 kDa ± 25.1) was slightly higher than that of the control group (149.4 kDa ± 23.1), there was no statistically significant difference between them (p > 0.05). However, the advantage of our in situ adhesion approach is the absence of a barrier like glue which can disrupt direct cellular communications between tissues.

SIGNIFICANCE

This study provides a novel method of directly combining tissue-engineered human bone with oral mucosa, which has the potential to improve cell-ingrowth and tissue integration. This engineered tissue construct, after further optimization, can be used clinically as a graft material in various oral surgeries and can also be employed as an in vitro model to investigate many aspects of oral diseases and examine dental materials and oral health care products as a replacement of in vivo models.

Fibroblast encapsulation in gelatin methacryloyl (GelMA) versus collagen hydrogel as substrates for oral mucosa tissue engineering

Purpose

Over the past decades, a variety of biomaterials have been investigated in terms of their suitability for oral mucosa tissue engineering. The aim of this study was to compare collagen and GelMA hydrogels as connective tissue scaffolds for fibroblasts and as substrates for seeding and culture of oral epithelial keratinocyte cells.

Methods

Human primary oral fibroblast and keratinocyte cells were isolated from gingival biopsies. The mixture of fibroblasts with GelMA or collagen gel were aliquoted within six-well tissue culture plate inserts and cross-linked using visible light or reconstitution buffer/heat, respectively. The viability of fibroblasts in the hydrogels was investigated after one and three days of cultivation using the PrestoBlue assay. Following the addition and culture of oral keratinocytes onto the connective tissue constructs, the tissue-engineered oral mucosa was assessed histologically.

Results

The tissue viability assay shows that collagen hydrogels encapsulating fibroblasts displayed significantly higher cell viability than cell-laden GelMA constructs after 24 and 72 h (p < 0.05). A stratified and differentiated epithelium has formed on the surface of cell-laden collagen hydrogel but not on the surface of the GelMA-based substrate.

Conclusion

Collagen-based scaffold offers superior biological properties compared to GelMA hydrogel in terms of oral fibroblast growth, as well as epithelial cell adhesion and differentiation. Therefore, collagen-based hydrogels remain the preferred choice for oral mucosa tissue engineering.

An Innovative Drug Delivery System Loaded with a Modified Combination of Triple Antibiotics for Use in Endodontic Applications

The objective of the current study was to introduce "Polylactic co-Glycolic Acid- (PLGA-) Coated Ceramic Microparticles" as an innovative drug delivery system, loaded with a new combination of triple antibiotics (penicillin G, metronidazole, and ciprofloxacin (PMC)) for use in endodontic treatments. Ceramic microparticles were made from β-tricalcium phosphate and hydroxyapatite and examined by "Scanning Electronic Microscope (SEM)." Then, fixed amounts of the selected antibiotics were added to a prepared PLGA solution and stirred thoroughly. Next, the prepared ceramic microparticles were dispersed completely in the drugs solution. The deposited "PMC-loaded PLGA-coated ceramic microspheres (PPCMs)" were dried and incubated in phosphate buffer saline (PBS) for 21 days. The drug release from PPCMs was quantified by a UV spectrophotometer. The antimicrobial activity of PPCMs was investigated using the "Agar Plate Diffusion Test (ADT)," "Minimum Inhibitory Concentration (MIC)," and "Minimum Bactericidal Concentration (MBC)" against Enterococcus faecalis (E. faecalis) and Aggregatibacter actinomycetemcomitans (A.a). The cell viability test (MTT) was conducted for cytotoxicity against human gingival fibroblasts. SEM micrographs of PPCMs showed spherical-like ceramic microparticles with smooth surfaces. Crystal-like antibiotic particles (chunks) were also found on PPCMs. Initial burst of antibiotics (31 µg/mL, 160 µg/mL, and 18 µg/mL for ciprofloxacin, metronidazole, and penicillin G, respectively, in the first 4 days) followed by gradual and sustained release was observed within a period of 21 days. PPCMs demonstrated pH close to normal physiological environment and antibacterial activity against E. faecalis and A.a in the first 2 days. MTT showed cell viability of more than 70% for PPCMs after 24 h and 72 h of exposure. In conclusion, PPCMs demonstrated satisfactory release of antibiotics, antibacterial activity against the selected microorganisms, and biocompatibility. Thus, PPCMs may be used to deliver modified triple antibiotics to the root canal system for use in endodontic applications.

Role of Iron on Physical and Mechanical Properties of Brushite Cements, and Interaction with Human Dental Pulp Stem Cells

Improving the physical, mechanical and biological properties of brushite cements (BrC) is of a great interest for using them in bone and dental tissue engineering applications. The objective of this study was to incorporate iron (Fe) at different concentrations (0.25, 0.50, and 1.00 wt.%) to BrC and study the role of Fe on phase composition, setting time, compressive strength, and interaction with human dental pulp stem cells (hDPSCs). Results showed that increase in Fe concentration increases the β-tricalcium phosphate (β-TCP)/ dicalcium phosphate dihydrate (DCPD) ratio and prolongs the initial and final setting time due to effective role of Fe on stabilizing the β-TCP crystal structure and retarding its dissolution kinetic, in a dose dependent manner where the highest setting time was recorded for 1.00 wt.% Fe-BrC sample. Addition of low concentrations of Fe (0.25 and 0.50 wt.%) did not have adverse effect on compressive strength and strength was in the range of 5.7-7.05 (±~1.4) MPa; however, presence of 1.00 wt.% Fe decreases the strength of BrC from 7.05 ± 1.57 MPa to 3.12 ± 1.06 MPa. Interaction between the BrCs and hDPSCs was evaluated by cell proliferation assay, scanning electron microscopy, and live/dead staining. Low concentrations of 0.25, and 0.50 wt.% of Fe did not have any adverse effect on cell attachment and proliferation; while significant decrease in cellular activity was evident in BrC samples doped with 1.00 wt. %. Together, these data show that low concentrations of Fe (equal or less than 0.50 wt. %) can be safely added to BrC without any adverse effect on physical, mechanical and biological properties in presence of hDPSCs.

A compound of concentrated growth factor and periodontal ligament stem cell-derived conditioned medium

The aim of this study was to determine the in vitro effect of a compound of concentrated growth factor (CGF) and periodontal ligament stem cell-derived conditioned medium (PDLSCs-CM) as a potential product for future applications in periodontal tissue regeneration. Isolated PDLSCs were characterized using flow cytometry and differentiation into osteoblasts and adipocytes cells. PDLSCs-CM and CGF were prepared and lyophilized. To determine the optimal concentration of the CGF-CM compound, the proliferation of PDLSCs after exposure to a wide range of different concentrations of CGF, CM, or their combination (CGF + CM) was investigated by methyl thiazol tetrazolium assay. Successful isolation of PDLSCs was confirmed by high expression of mesenchymal surface markers and differentiation into osteoblasts and adipocytes. PDLSCs showed higher proliferation in the 6.25 mg/mL concentration of CM and 94 μg/mL concentration of CGF. High concentrations of CGF and CM markedly inhibited the proliferation of PDLCs (p < 0.05). The exposure of PDLSCs to the compound of 10% CM + 90% CGF significantly increased the cell proliferation (p < 0.05). The results showed that CGF, CM, or their combination exert a proliferative effect on cells at a certain concentration. Further investigation on the synergistic effect of this compound may approve its application for periodontal regeneration.

Three-Dimensional In Vitro Oral Mucosa Models of Fungal and Bacterial Infections

Oral mucosa is the target tissue for many microorganisms involved in periodontitis and other infectious diseases affecting the oral cavity. Three-dimensional (3D) in vitro and ex vivo oral mucosa equivalents have been used for oral disease modeling and investigation of the mechanisms of oral bacterial and fungal infections. This review was conducted to analyze different studies using 3D oral mucosa models for the evaluation of the interactions of different microorganisms with oral mucosa. In this study, based on our inclusion criteria, 43 articles were selected and analyzed. Different types of 3D oral mucosa models of bacterial and fungal infections were discussed in terms of the biological system used, culture conditions, method of infection, and the biological endpoints assessed in each study. The critical analysis revealed some contradictory reports in this field of research in the literature. Challenges in recovering bacteria from oral mucosa models were further discussed, suggesting possible future directions in microbiomics, including the use of oral mucosa-on-a-chip. The potential use of these 3D tissue models for the evaluation of the effects of antiseptic agents on bacteria and oral mucosa was also addressed. This review concluded that there were many aspects that would require optimization and standardization with regard to using oral mucosal models for infection by microorganisms. Using new technologies-such as microfluidics and bioreactors-could help to reproduce some of the physiologically relevant conditions and further simulate the clinical situation. Impact statement Tissue-engineered or commercial models of the oral mucosa are very useful for the study of diseases that involve the interaction of microorganisms and oral epithelium. In this review, challenges in recovering bacteria from oral mucosa models, the potential use of these three-dimensional tissue models for the evaluation of the effects of antiseptic agents, and future directions in microbiomics are discussed.

In vitro and in vivo effects of concentrated growth factor on cells and tissues

This article reviews the biological outcome of the concentrated growth factor (CGF), a new platelet derivative used for tissue regeneration, in published articles related to the use of this product in basic and clinical studies. An electronic literature research using PubMed and SCOPUS was performed using combination of keywords: "concentrated growth factor" (OR "CGF"), AND "stem cells," AND "cells" OR "cell proliferation" OR "cell migration" OR "cell differentiation," AND "repair" OR "survival" OR "revitalization," AND "tissue" OR "bone." Forty-five articles that were published between 2012 and 2020 met the inclusion criteria. These studies have used CGF as fresh solid form, freeze-dried, membrane, extract, or exudate. Most studies demonstrate the positive effects of CGF in a dose-dependent manner under certain concentrations. Studies comparing CGF with other platelet concentrates, report lower efficiency, no statistically significant differences, or better results for CGF. Combination of CGF with stem cells and biomaterials significantly improves bone regeneration and the effect of allograft or collagen membrane is better than CGF alone. For a better examination of the biological outcomes of CGF, the standardization of CGF preparation regarding the choice of the test tube material for blood collection, the required volume of blood, the necessary count of platelets in CGF, and the most appropriate type of CGF are recommended.

In vitro study of surface alterations to polyetheretherketone and titanium and their effect upon human gingival fibroblasts

STATEMENT OF PROBLEM

Soft-tissue attachment to different surfaces may play a pivotal role in the long-term success of dental implants. However, studies on the issue, especially on newer materials, are sparse.

PURPOSE

The purpose of this in vitro study was to evaluate the viability and adhesion of human gingival fibroblasts (HGFs) on different implant abutment materials with specific surface modifications.

MATERIAL AND METHODS

One hundred and fifty specimens in 6 experimental groups were evaluated: smooth-machined titanium alloy (Ti), laser-modified titanium (TiL), smooth-machined polyetheretherketone (PEEK) (P), laser-modified PEEK (PL), plasma-treated PEEK (PP), laser- and plasma-treated PEEK (PLP). Machined Ti was considered as the control group. Surface roughness (S_a), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) were measured. HGF attachment and proliferation were observed at 1, 3, and 7 days after cell seeding. Comparison of the means among the groups was performed with 1-way analysis of variance (ANOVA) with post hoc comparison using the Tukey test (α=.05).

RESULTS

S_a values of the laser modified groups were significantly higher than those of the nonmodified (smooth-machined) groups (P<.001). WCAs were significantly different among PEEK groups, and plasma-sprayed groups had the lowest WCAs. XPS analysis of both Ti and PEEK groups showed laser treatment did not have any significant effect on the surface composition of the PEEK as the same bonds with similar ratio/fraction were detected in the spectrum of the modified specimens. Scanning electron microscopy (SEM) revealed more functionally oriented HGF cells on the laser-grooved surfaces. On the first, third, and seventh day of proliferation, the titanium groups showed no significant differences (P>.05). On the first and third days of proliferation, the plasma sprayed groups (PP, PLP) showed significantly greater proliferation than all experimental groups (P<.001). On the seventh day of proliferation, statistically significant differences were observed between all PEEK groups and between all PEEK groups and the Ti group (P<.001), with the exception of the PL and P groups and the PLP and Ti groups (P>.05).

CONCLUSIONS

Laser-modified titanium and PEEK surfaces led to guided gingival fibroblast attachment. Plasma treatment of PEEK surfaces increased the wettability of this polymer and improved proliferation of HGF.

Culture of dental pulp stem cells on nanoporous alumina substrates modified by carbon nanotubes

PURPOSE

Alumina substrates are one of the commonly used scaffolds applied in cell culture, but in order to prevent formation of biofilm on the alumina substrate, these substrates are modified with carbon nanotube.

METHODS

The alumina substrate was made by a two-step anodization method and was then modified with carbon nanotubes by simple chemical reaction. The substrates were characterized with FTIR, SEM, EDX, 3D laser scanning digital microscope, contact angle (CA) and surface free energy (SFE). To determine how this modification influences the reduction of biofilm, biofilm of two various bacteria, Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus), were investigated.

RESULTS

The biofilm on the modified substrate decreased due to the presence of carbon nanotubes and increased antibacterial properties. Dental pulp stem cells (DPSCs) were cultured onto flat alumina (FA) and nanoporous alumina-multiwalled carbon nanotubes (NAMC) substrates to examine how the chemical modification and surface topography affects growth of DPSCs.

CONCLUSION

Cell attachment and proliferation were investigated with SEM and Presto Blue assay, and the findings show that the NAMC substrates are suitable for cell culture.

Multiple fractures in infants who have Ehlers-Danlos/hypermobility syndrome and or vitamin D deficiency: A case series of 72 infants whose parents were accused of child abuse and neglect

Objective: To increase the level of awareness that Ehlers-Danlos/hypermobility syndrome (EDS) and vitamin D deficiency are associated with infantile fragility fractures and radiologic features that may be mistakenly reported to be caused by non-accidental trauma due to Child Abuse and Neglect (CAN).

Patients and Methods: We constructed a case series, the largest to date, of infants with EDS who were vitamin D sufficient, insufficient and deficient and infants without EDS but with documented vitamin D deficiency and radiologic evidence of rickets who presented with multiple fractures originally diagnosed as being non-accidental and caused by child abuse. These infants were referred to the outpatient Bone Health Care Clinic at Boston University Medical Campus over a 6-year (2010–2015) period. We also present 6 index cases in which the court concluded that there was no convincing evidence of child abuse and the infants were returned to their parents. Institutional Review Board (IRB) approval was obtained.

Results: We present 72 cases of infants with multiple fractures diagnosed to be caused by non-accidental trauma. All infants were younger than one year of age. Among them, 93%(67) had clinical evidence of EDS and/or a family history with a confirmed clinical diagnosis of at least one parent having EDS and the other 7%(5) without evidence of EDS had vitamin D deficiency/infantile rickets. Three of the EDS infants were diagnosed as osteogenesis imperfecta (OI)/EDS overlap syndrome. The most common fractures noted at diagnosis were ribs and extremity fractures (including classic metaphyseal lesions). Serum levels of 25-hydroxyvitamin D [25(OH)D] were reported in 48 infants (18.0 ± 8.5 ng/ml) and in 30 mothers (21.3 ± 11.7 ng/ml). Sixty-three percent (27) of the EDS infants who had their serum 25(OH)D measured were vitamin D deficient 25(OH)D<20 ng/ml and 5 were vitamin D sufficient 25(OH)D>30 ng/ml. The mean serum level for infants with vitamin D deficiency/rickets was (10.2 ± 3.0 ng/ml)

Conclusion: EDS, OI/EDS and vitamin D deficiency/infantile rickets are associated with fragility fractures in infants that can be misinterpreted as caused by non-accidental trauma due to child abuse.