Microfluidic nanoprecipitation of PEGylated PLGA nanoparticles with rapamycin and performance evaluation

Rapamycin (RAP) is currently being developed as potential antibreast cancer drug. However, its poor solubility completely limits its use. The aim of this study was to develop polyethylene glycol-poly(lactide-co-glycolide) (PEG-PLGA)-based nanoparticles (NPs) to load RAP via microfluidics with an appropriate polyethylene glycol (PEG) content to enhance the bioavailability of RAP. Polydimethylsiloxane (PDMS) chips with a Y-shaped channel were designed to obtain RAP-loaded PEG-PLGA NPs (RAP-PEG-PLGA). The entrapment efficiency (EE) and drug loading (DL) as well as release profile of RAP-PEG-PLGA were evaluated, and their resistance to plasma albumin adsorption of NPs with different PEG contents was evaluated and compared. RAW264.7 and 4T1 cells were used to assess the antiphagocytic and anticancer cells effect of NPs, respectively. RAP-PEG-PLGA of around 124 nm in size were successfully prepared with the EE of 82.0% and DL of 12.3%, and sustained release for around 40 d. A PEG relative content of 10% within the PEG-PLGA molecule was shown superior in resisting protein adsorption. RAP-PEG-PLGA inhibited the growth of breast cancer cells when the concentration was over 10 μg/mL, and the inhibition efficiency was significantly higher than free RAP. Hence, the current RAP-PEG-PLGA could be a potential therapeutic system for breast cancer treatment.

An injectable gel based on photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles for periodontitis treatment

Guided bone regeneration (GBR) is an effective strategy to promote periodontal tissue repair. The current study aimed to develop an injectable gel for GBR, composed of photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles (MBGNs) loaded with antibacterial minocycline hydrochloride (MNCl). Hyaluronic acid modified with methacrylic anhydride (MHA) that could be cross-linked under UV irradiation was first synthesized. Dynamic rheological evaluation of MHA under UV was carried out to determine its in-situ gelling feasibility and stability. Morphological and mechanical characterization was performed to determine the optimal concentration of MHA gels. Sol-gel derived MBGNs loaded with MNCl were further incorporated into MHA gels to obtain the injectable drug-loaded MBGN-MNCl/MHA gels. In vitro antibacterial, anti-inflammatory and osteogenic effects of this gel were evaluated. It was shown that the MHA gel obtained from 3 % MHA under UV treatment of 30s exhibited a suitable porous structure with a compressive strength of 100 kPa. MBGNs with particle size of ∼120 nm and mesopores were confirmed by TEM and SEM. MBGNs had a loading capacity of ∼120 mg/g for MNCl, exhibiting a sustained release behavior. The MBGN-MNCl/MHA gel was shown to effectively inhibit the proliferation of Streptococcus mutans and the expression of pro-inflammatory factors IL-6 and TNF-α by macrophages. It could on the other hand significantly promote the expression of osteogenic-related genes ALP, Runx2, OPN, and osterix of MC3T3-E1 cells. In conclusion, the current design using photo-crosslinkable MHA gel embedded with MNCl loaded MBGNs can serve as a promising injectable formulation for GBR treatment of irregular periodontal defects.

Modulation of immunosuppressive effect of rapamycin via microfluidic encapsulation within PEG-PLGA nanoparticles

The high hydrophobicity and low oral availability of immunosuppressive drug, rapamycin, seriously limit its application. It was thus aimed to develop a PEG-PLGA based nano-loading system for rapamycin delivery to achieve improved bioavailability with sustained effects via a novel microfluidic chip and manipulation of the hydrophobic PLGA chain length. PDMS based microfluidic chip with Y shape was designed and PEG-PLGA polymers with different PLGA chain length were used to prepare rapamycin nano-delivery systems. Dendritic cells were selected to evaluate the immunosuppressive effect of the nanoparticles including cytotoxicity assay, dendritic cell activation, and cytokine levels. The effects of different PEG-PLGA nanoparticles on the immunomodulatory properties were finally compared. It was shown that PEG-PLGA could be successfully used for rapamycin encapsulation via microfluidics to obtain nano-delivery systems (Rapa&P-20 k, Rapa&P-50 k and Rapa&P-95 k) ranging from 100 nm to 116 nm. The encapsulation efficiency was ranged from 69.70% to 84.55% and drug loading from 10.45% to 12.68%. The Rapa&P-50 k (PLGA chain length: 50 k) could achieve the highest drug loading (DL) and encapsulation efficiency (EE) as 12.68% and 84.55%. The encapsulated rapamycin could be gradually released from three nanoparticles for more than 1 month without any noticeable burst release. The Rapa & P nanoparticles exhibited enhanced immunosuppressive effects over those of free rapamycin as shown by the expression of CD40 and CD80, and the secretion of IL-1β, IL-12 and TGF-β1. Rapa&P-50 k nanoparticles could be the optimal choice for rapamycin delivery as it also achieved the most effective immunosuppressive property. Hence, this study could provide an efficient technology with superior manipulation to offer a solution for rapamycin delivery and clinical application.

Synergetic effect of 3D porous microsphere structure and activation of adenosine A2B receptor signal on promoting osteogenic differentiation of BMSCs

Biodegradable microspheres offer great potential as functional building blocks for bottom-up bone tissue engineering. However, it remains challenging to understand and regulate cell behaviors in fabrication of injectable bone microtissues using microspheres. The study aims to develop an adenosine functionalized poly (lactide-co-glycolide) (PLGA) microsphere to enhance cell loading efficiency and inductive osteogenesis potential, and subsequently to investigate adenosine signaling-mediated osteogenic differentiation in cells grown on three-dimensional (3D) microspheres and flat control. Adenosine was loaded on PLGA porous microspheres via polydopamine coating, and the cell adhesion and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) were improved on these microspheres. It was found that adenosine A2B receptor (A2BR) was further activated by adenosine treatment, which consequently enhanced osteogenic differentiation of BMSCs. This effect was more obvious on 3D microspheres compared to 2D flats. However, the promotion of osteogenesis on the 3D microspheres was not eliminated by blocking the A2BR with antagonist. Finally, adenosine functionalized microspheres could fabricate injectable microtissues in vitro, and improve cell delivery and osteogenic differentiation after injection in vivo. Therefore, it is considered that adenosine loaded PLGA porous microspheres will be of good value in minimally invasive injection surgery and bone tissue repair.

Manipulation of porous poly(l-lactide-co-ε-caprolactone) microcarriers via microfluidics for C2C12 expansion

The growth and repair of skeletal muscle are due in part to activation of muscle precursor cells, commonly known as satellite cells or myoblasts. In order to acquire enough cells for neoskeletal muscle regeneration, it is urgent to develop microcarriers for skeletal myoblasts proliferation with a considerable efficiency. The current study was thus proposed to develop a microfluidic technology to manufacture porous poly(l-lactide-co-ε-caprolactone) (PLCL) microcarriers of high uniformity, and porosity was manipulated via camphene to suit the proliferation of C2C12 cells. A co-flow capillary microfluidic device was first designed to obtain PLCL microcarriers with different porosity. The attachment and proliferation of C2C12 cells on these microcarriers were evaluated and the differentiation potential of expanded cells were verified. The obtained porous microcarriers were all uniform in size with a high mono-dispersity (CV < 5 %). The content of camphene rendered effects on the size, porosity, and pore size of microcarriers, and porous structure addition produced a softening of their mechanical properties. The one of 10 % camphene (PM-10) exhibited the superior expansion for C2C12 cells with the number of cells after 5 days of culture reached 9.53 times of the adherent cells on the first day. The expanded cells from PM-10 still retained excellent myogenic differentiation performance as the expressions of MYOD, Desmin and MYH2 were intensively enhanced. Hence, the current developed porous PLCL microcarriers could offer as a promising type of substrates not only for in vitro muscular precursor cells expansion without compromising any multipotency but also have the potential as injectable constructs to mediate muscle regeneration.

Preparation of extracellular matrix of fish swim bladders by decellularization with supercritical carbon dioxide

Fish swim bladders used to be considered as byproducts or waste in fishery; however, they are potential materials for biological medicine with abundant collagen. In this work, an efficient noncytotoxic decellularization process using sodium dodecyl sulfate (SDS) ternary system assisted with supercritical carbon dioxide (scCO2) as the green extraction fluid and ethanol (ET) as the cosolvent has been developed to harvest acellular fish swim bladders (AFSBs). The experimental results show that the tissue treated by SDS assisted with scCO2 and ethanol at 37 °C and 25 MPa can be decellularized thoroughly and maintains intact fibers and uniform pore distribution, which resulting in a tensile strength of 5.61 MPa and satisfactory biocompatibility. Meanwhile, the residual SDS content in scCO2/SDS/ET ternary system is 0.0122% which is significantly lower than it in scCO2/SDS system due to the enhanced mass transfer rate of SDS in tissues by scCO2 with ethanol. The synergy between SDS and ethanol can enhance the diffusion coefficient and the solubility of SDS in scCO2, which reduced the contact time between SDS and tissues. Meaningfully, the results obtained in this work can not only provide a novel strategy to produce acellular matrix with superior properties, but also offer a further understanding of the decellularization through scCO2 extraction processing with the synergy of suitable detergent/cosolvent.

Controllable manipulation of alginate-gelatin core-shell microcarriers for HUMSCs expansion

Human umbilical cord mesenchymal stem cells (HUMSCs) are one of the most attractive sources of stem cells, and it is meaningful to design and develop a type of microcarriers with suitable mechanical strength for HUMSCs proliferation in order to acquire enough cells for cell-based therapy. Alginate-gelatin core-shell (AG) soft microcarriers were thus fabricated via a microfluidic device with droplet shearing/gelation facilities and surface coating for in vitro expansion of HUMSCs. The attachment and proliferation of HUMSCs on AG microcarriers with different mechanical strengths modulated by gelatin coating was studied, and the harvested cells were characterized to verity their differentiation potential. The obtained core-shell microcarriers were all uniform in size with a high mono-dispersity (CV < 5 %). An increase in the gelatin surface coating concentration from 0.5 % to 1.5 % would lead to the reduction in both the particle size of the microcarriers and swelling ratio upon the contact of culture medium, but increased elastic modulus. Microcarriers of 245.12 μm with a gelatin coating elastic modulus of 27.5 kPa (AG10) were found to be the optimal substrate for HUMSCs with an initial attachment efficiency of 44.41 % and a 5-day expansion efficiency of 647 %. The cells harvested from AG10 still reserved their outstanding pluripotency. Fresh AG10 could smoothly transfer cells from a running microcarrier-cell system of confluence to serve as a convenient way of scaling-up the existing culture. The current study thus developed suitable microcarriers, AG10, for in vitro HUMSCs expansion with well reserve of cell multipotency, and also provided a manufacturing and surface manipulating strategy of precise production and fine regulation of microcarrier properties.

Fabrication and Characterization of Collagen/PVA Dual-Layer Membranes for Periodontal Bone Regeneration

Guided tissue regeneration (GTR) is a promising treatment for periodontal tissue defects, which generally uses a membrane to build a mechanical barrier from the gingival epithelium and hold space for the periodontal regeneration especially the tooth-supporting bone. However, existing membranes possess insufficient mechanical properties and limited bioactivity for periodontal bone regenerate. Herein, fish collagen and polyvinyl alcohol (Col/PVA) dual-layer membrane were developed via a combined freezing/thawing and layer coating method. This dual-layer membrane had a clear but contact boundary line between collagen and PVA layers, which were both hydrophilic. The dual membrane had an elongation at break of 193 ± 27% and would undergo an in vitro degradation duration of more than 17 days. Further cell experiments showed that compared with the PVA layer, the collagen layer not only presented good cytocompatibility with rat bone marrow-derived mesenchymal stem cells (BMSCs), but also promoted the osteogenic genes (RUNX2, ALP, OCN, and COL1) and protein (ALP) expression of BMSCs. Hence, the currently developed dual-layer membranes could be used as a stable barrier with a stable degradation rate and selectively favor the bone tissue to repopulate the periodontal defect. The membranes could meet the challenges encountered by GTR for superior defect repair, demonstrating great potential in clinical applications.

Microfluidic preparation of PLGA composite microspheres with mesoporous silica nanoparticles for finely manipulated drug release

The current study explored the feasibility of a microfluidic preparation of PLGA composite microspheres with mesoporous silica nanoparticles (MSNs) to finely manipulate the drug release behaviors of the microspheres. MSNs were synthesized via a hydrothermal method, and PLGA microspheres loaded with MSNs (PLGA-MSNs) were prepared using a capillary-based three-phase microfluidic device. Drug loading and release behaviors using rhodamine B (RB) as a water-soluble model drug were investigated and compared with those of PLGA microspheres. MSNs with an average particle size of 119 nm, a specific surface area of 902.5 cm²/g, and a pore size of approximately 5 nm were obtained. The mean diameter of PLGA-MSNs was 56 μm (CV = 4.91%). A sustained release duration of encapsulated RB from PLGA-MSNs for 4 months was achieved without any observable burst release. PLGA microspheres with monodispersion could also allow for a similar release duration of encapsulated RB but encountered a burst release in the mid-term of the studied duration. PLGA-MSNs had a denser outer PLGA layer and a more centralized hollow hole than PLGA microspheres without MSNs. Hence, the incorporation of MSNs into PLGA microspheres via microfluidics could be an efficient strategy to finely tune the drug release behavior of PLGA microspheres.

Fabrication of PCL Scaffolds by Supercritical CO2 Foaming Based on the Combined Effects of Rheological and Crystallization Properties

Polycaprolactone (PCL) scaffolds have recently been developed via efficient and green supercritical carbon dioxide (scCO₂) melt-state foaming. However, previously reported gas-foamed scaffolds sometimes showed insufficient interconnectivity or pore size for tissue engineering. In this study, we have correlated the thermal and rheological properties of PCL scaffolds with their porous morphology by studying four foamed samples with varied molecular weight (MW), and particularly aimed to clarify the required properties for the fabrication of scaffolds with favorable interconnected macropores. DSC and rheological tests indicate that samples show a delayed crystallization and enhanced complex viscosity with the increasing of MW. After foaming, scaffolds (27 kDa in weight-average molecular weight) show a favorable morphology (pore size = 70–180 μm, porosity = 90% and interconnectivity = 96%), where the lowest melt strength favors the generation of interconnected macropore, and the most rapid crystallization provides proper foamability. The scaffolds (27 kDa) also possess the highest Young’s modulus. More importantly, owing to the sufficient room and favorable material transportation provided by highly interconnected macropores, cells onto the optimized scaffolds (27 kDa) perform vigorous proliferation and superior adhesion and ingrowth, indicating its potential for regeneration applications. Furthermore, our findings provide new insights into the morphological control of porous scaffolds fabricated by scCO₂ foaming, and are highly relevant to a broader community that is focusing on polymer foaming.

Induction of zonal-specific cellular morphology and matrix synthesis for biomimetic cartilage regeneration using hybrid scaffolds

Cartilage is anisotropic in nature and organized into distinct zones. Our goal was to develop zonal-specific three-dimensional hybrid scaffolds which could induce the generation of zonal-specific cellular morphology and extracellular matrix (ECM) composition. The superficial and middle zones comprised two layers of hyaluronic acid (HA) hydrogel which enveloped specifically orientated or randomly arranged polylactic acid nanofibre meshes. The deep zone comprised a HA hydrogel with multiple vertical channels. Primary bovine chondrocytes were seeded into the individual zonal scaffolds, cultured for 14 days and then the ECM was analysed. The aligned nanofibre mesh used in the superficial zone induced an elongated cell morphology, lower glycosaminoglycan (GAG) and collagen II production, and higher cell proliferation and collagen I production than the cells in the middle zone scaffold. Within the middle zone scaffold, which comprised a randomly orientated nanofibre mesh, the cells were clustered and expressed more collagen II. The deep zone scaffold induced the highest GAG production, the lowest cell proliferation and the lowest collagen I expression of the three zones. Assembling the three zones and stabilizing the arrangement with a HA hydrogel generated aligned, randomly aggregated and columnar cells in the superficial, middle and deep zones. This study presents a method to induce zonal-specific chondrocyte morphology and ECM production.

Glutamate transporter GLT1 inhibitor dihydrokainic acid impairs novel object recognition memory performance in mice

Glutamate transporter GLT1 mediates glutamate uptake, and maintains glutamate homeostasis in the synaptic cleft. Previous studies suggest that blockade of glutamate uptake affects synaptic transmission and plasticity. However, the effect of GLT1 blockade on learning and memory still receives little attention. In the present study, we examined the effect of unilateral intracerebroventricular injection of dihydrokainic acid (DHK), a GLT-1 inhibitor, on novel object recognition (NOR) memory performance. The NOR task involved three sessions including habituation, sampling and test. In experiment 1, DHK injection 0.5 h pre-sampling impaired short-term NOR memory performance. In experiment 2, DHK injection 0.5 h pre-sampling impaired long-term NOR memory acquisition. In experiment 3, DHK injection immediately but not 6 h post-sampling impaired long-term NOR memory consolidation. In experiment 4, DHK injection 0.5 h pre-test impaired long-term NOR memory retrieval. Furthermore, DHK-induced memory performance impairment was not due to its effects on nonspecific responses such as locomotor activity and exploratory behavior. The current findings further extend previous studies on the effects of disruption of glutamate homeostasis on learning and memory.

Human tRNA-Derived Small RNAs Modulate Host-Oral Microbial Interactions

Coevolution of the human host and its associated microbiota has led to sophisticated interactions to maintain a delicate homeostasis. Emerging evidence suggests that in addition to small molecules, peptides, and proteins, small regulatory noncoding RNAs (sRNAs) might play an important role in cross-domain interactions. In this study, we revealed the presence of diverse host transfer RNA-derived small RNAs (tsRNAs) among human salivary sRNAs. We selected 2 tsRNAs (tsRNA-000794 and tsRNA-020498) for further study based on their high sequence similarity to specific tRNAs from a group of Gram-negative oral bacteria, including Fusobacterium nucleatum, a key oral commensal and opportunistic pathogen. We showed that the presence of F. nucleatum triggers exosome-mediated release of tsRNA-000794 and tsRNA-020498 by human normal oral keratinocyte cells. Furthermore, both tsRNA candidates exerted a growth inhibition effect on F. nucleatum, likely through interference with bacterial protein biosynthesis, but did not affect the growth of Streptococcus mitis, a health-associated oral Gram-positive bacterium whose genome does not carry sequences bearing high similarity to either tsRNA. Our data provide the first line of evidence for the modulatory role of host-derived tsRNAs in the microbial-host interaction.

Microbiome Associated with Severe Caries in Canadian First Nations Children

Young Indigenous children in North America suffer from a higher degree of severe early childhood caries (S-ECC) than the general population, leading to speculation that the etiology and characteristics of the disease may be distinct in this population. To address this knowledge gap, we conducted the first microbiome analysis of an Indigenous population using modern molecular techniques. We investigated the caries-associated microbiome among Canadian First Nations children with S-ECC. Thirty First Nations children <72 mo of age with S-ECC and 20 caries-free children were recruited in Winnipeg, Canada. Parents or caregivers completed a questionnaire on general and dental health, diet, and demographics. The plaque microbiome was investigated by sequencing the 16S rRNA gene. Sequences were clustered into operational taxonomic units and taxonomy assigned via the Human Oral Microbiome Database, then analyzed at the community level with alpha and beta diversity measures. Compared with those who were caries free, children with S-ECC came from households with lower income; they were more likely to live in First Nations communities and were more likely to be bottle-fed; and they were weaned from the bottle at a later age. The microbial communities of the S-ECC and caries-free groups did not differ in terms of species richness or phylogenetic diversity. Beta diversity analysis showed that the samples significantly clustered into groups based on caries status. Twenty-eight species-level operational taxonomic units were significantly different between the groups, including Veillonella HOT 780 and Porphyromonas HOT 284, which were 4.6- and 9-fold higher, respectively, in the S-ECC group, and Streptococcus gordonii and Streptococcus sanguinis, which were 5- and 2-fold higher, respectively, in the caries-free group. Extremely high levels of Streptococcus mutans were detected in the S-ECC group. Overall, First Nations children with S-ECC have a significantly different plaque microbiome than their caries-free counterparts, with the S-ECC group containing higher levels of known cariogenic organisms.

Arginine Improves pH Homeostasis via Metabolism and Microbiome Modulation

Dental caries can be described as a dysbiosis of the oral microbial community, in which acidogenic, aciduric, and acid-adapted bacterial species promote a pathogenic environment, leading to demineralization. Alkali generation by oral microbes, specifically via arginine catabolic pathways, is an essential factor in maintaining plaque pH homeostasis. There is evidence that the use of arginine in dentifrices helps protect against caries. The aim of the current study was to investigate the mechanistic and ecological effect of arginine treatment on the oral microbiome and its regulation of pH dynamics, using an in vitro multispecies oral biofilm model that was previously shown to be highly reflective of the in vivo oral microbiome. Pooled saliva from 6 healthy subjects was used to generate overnight biofilms, reflecting early stages of biofilm maturation. First, we investigated the uptake of arginine by the cells of the biofilm as well as the metabolites generated. We next explored the effect of arginine on pH dynamics by pretreating biofilms with 75 mM arginine, followed by the addition of sucrose (15 mM) after 0, 6, 20, or 48 h. pH was measured at each time point and biofilms were collected for 16S sequencing and targeted arginine quantification, and supernatants were prepared for metabolomic analysis. Treatment with only sucrose led to a sustained pH drop from 7 to 4.5, while biofilms treated with sucrose after 6, 20, or 48 h of preincubation with arginine exhibited a recovery to higher pH. Arginine was detected within the cells of the biofilms, indicating active uptake, and arginine catabolites citrulline, ornithine, and putrescine were detected in supernatants, indicating active metabolism. Sequencing analysis revealed a shift in the microbial community structure in arginine-treated biofilms as well as increased species diversity. Overall, we show that arginine improved pH homeostasis through a remodeling of the oral microbial community.

Well-defined and biocompatible hydrogels with toughening and reversible photoresponsive properties

In the present study, novel hydrogels with extremely high strength, reversible photoresponsive and excellent biocompatible properties were prepared. The functional hydrogels were synthesized from a well-defined poly (ethylene glycol) polymer with spiropyran groups at a given position (PEG-SP) via a Cu(i)-catalyst Azide-Alkyne Cycloaddition (CuAAC) reaction. The molecular structures of the sequential intermediates for PEG-SP hydrogel preparation were verified by (1)HNMR and FT-IR. The mechanical property, swelling ratio, compression strength, surface hydrophilicity, and biocompatibility of the resulting hydrogel were characterized. Since spiropyran is pivotal to the switch in hydrophilicity on the hydrogel surface, the swelling ratio of PEG-SP hydrogel under Vis irradiation has a major decrease (155%). Before and after UV light irradiation, the contact angle of the hydrogel has a change of 13.8°. The photoresponsive property of this hydrogel was thus demonstrated, and such a property was also shown to be reversible. The well-defined PEG-SP hydrogel can also sustain a compressive stress of 49.8 MPa without any macro- or micro-damage, indicating its outstanding mechanical performance. Furthermore, it possessed excellent biocompatibility as demonstrated by its performance in an in vivo porcine subcutaneous implantation environment. No inflammation was observed and it got along well with the adjacent tissue. The above features indicate that PEG-SP hydrogels are promising as an implantable matrix for potential applications in biomaterial.

An injectable scaffold based on crosslinked hyaluronic acid gel for tissue regeneration

An injectable scaffold of crosslinked hyaluronic acid gel for tissue regeneration.

PDL regeneration via cell homing in delayed replantation of avulsed teeth

Background

This study was aimed to investigate whether regeneration of periodontal ligament (PDL) like tissue could be promoted by stromal cell-derived factor-1 (SDF1) and bone morphogenetic protein-7 (BMP7) induced cell homing in delayed replantation of avulsed teeth.

Methods

Canine mandibular premolar teeth were first extracted and air-dried for 2 h followed by complete detachment of their PDL tissues. The crown and pulp of the teeth were also removed. Twenty-four roots divided into two groups (n = 12/group) were used for the following in vivo transplantation. The roots of Group A were treated with 17 % EDTA for 24 h to achieve demineralization, and then coated with SDF1 and BMP7 supplemented collagen solution. The roots of Group B were similarly treated except being coated with a pristine collagen solution. The above roots were transplanted in the sockets that formed previously during tooth extraction. At 6 months’ post-operation, PDL-like tissue composed of spindle-shaped cells, capillaries and highly organized collagen fibers was observed in the interstitial space between the avulsed root surface and surrounding alveolar bone in Group A. The neo-fibers inserted deeply and perpendicularly into the cementum and adjacent bone. The periodontium-like characteristics of the neo-tissue was confirmed by immunohistochemical staining for collagen I, fibronectin and osteocalcin.

Results

A high incidence of PDL re-establishment as 42 % was achieved for samples of Group A. However, no PDL-like tissue was found but root ankylosis and replacement resorption as well as inflammatory resorption was observed in the replanted roots of Group B.

Conclusions

It can be confirmed that avulsed teeth could be successfully rescued even in delayed transplantation to avoid dentoalveolar ankylosis or replacement resorption via the current developed cell homing method.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0719-2) contains supplementary material, which is available to authorized users.

Cellular Components Mediating Coadherence of Candida albicans and Fusobacterium nucleatum

Candida albicans is an opportunistic fungal pathogen found as part of the normal oral flora. It can be coisolated with Fusobacterium nucleatum, an opportunistic bacterial pathogen, from oral disease sites, such as those involved in refractory periodontitis and pulp necrosis. The physical coadherence between these 2 clinically important microbes has been well documented and suggested to play a role in facilitating their oral colonization and colocalization and contributing to polymicrobial pathogenesis. Previous studies indicated that the physical interaction between C. albicans and F. nucleatum was mediated by the carbohydrate components on the surface of C. albicans and the protein components on the Fusobaterium cell surface. However, the identities of the components involved still remain elusive. This study was aimed at identifying the genetic determinants involved in coaggregation between the 2 species. By screening a C. albicans SN152 mutant library and a panel of F. nucleatum 23726 outer membrane protein mutants, we identified FLO9, which encodes a putative adhesin-like cell wall mannoprotein of C. albicans and radD, an arginine-inhibitable adhesin-encoding gene in F. nucleatum that is involved in interspecies coadherence. Consistent with these findings, we demonstrated that the strong coaggregation between wild-type F. nucleatum 23726 and C. albicans SN152 in an in vitro assay could be greatly inhibited by arginine and mannose. Our study also suggested a complex multifaceted mechanism underlying physical interaction between C. albicans and F. nucleatum and for the first time revealed the identity of major genetic components involved in mediating the coaggregation. These observations provide useful knowledge for developing new targeted treatments for disrupting interactions between these 2 clinically relevant pathogens.

Reconstructing spinal dura-like tissue using electrospun poly(lactide-co-glycolide) membranes and dermal fibroblasts to seamlessly repair spinal dural defects in goats

Many neuro- and spinal surgeries involving access to the underlying nervous tissue will cause defect of spinal dural mater, further resulting in cerebrospinal fluid leakage. The current work was thus aimed to develop a package which included two layers of novel electrospun membranes, dermal fibroblasts and mussel adhesive protein for repairing spinal dural defect. The inner layer is electrospun fibrous poly(lactide-co-glycolide) membrane with oriented microstructure (O-poly(lactide-co-glycolide)), which was used as a substrate to anchor dermal fibroblasts as seed cells to reconstitute dura-like tissue via tissue engineering technique. The outer layer is chitosan-coated electrospun nonwoven poly(lactide-co-glycolide) membrane (poly(lactide-co-glycolide)-chitosan). During surgery, the inner reconstituted tissue layer was first used to directly cover dura defects, while the outer layer was placed onwards with its marginal area tightly immobilized to the surrounding normal spinal dura aided by mussel adhesive protein. Efficacy of the current design was verified in goats with spinal dural defects (0.6 cm × 0.5 cm) in lumbar. It was shown that seamless and quick sealing of the defect area with the implants was realized by mussel adhesive protein. Guided tissue growth and regeneration in the defects of goats were observed when they were repaired by the current package. Effective cerebrospinal fluid containment and anti-adhesion of the regenerated tissue to the surrounding tissue could be achieved in the current animal model. Hence, it could be ascertained that the current package could be a favorite choice for surgeries involving spinal dural defects.

Regeneration of dentin–pulp-like tissue using an injectable tissue engineering technique

An injectable tissue engineering technique to regenerate dentin–pulp complex.

Stimuli-responsive hydrogels prepared by simultaneous “click chemistry” and metal–ligand coordination

A novel strategy to synthesize stimuli-responsive metal-coordinated polymeric gels (MCPGs) via one-pot CuAAC and non-covalent metal coordination chemistry was demonstrated.

MMP-9 inhibitor SB-3CT attenuates behavioral impairments and hippocampal loss after traumatic brain injury in rat

The aim of this study was to evaluate the potential efficacy of SB-3CT, a matrix metallopeptidase 9 inhibitor, on behavioral and histological outcomes after traumatic brain injury (TBI) in rats. Adult male Sprague-Dawley rats were randomly divided into three groups (n=15/group): TBI with SB-3CT treatment, TBI with saline, and sham injury. The TBI model was induced by a fluid percussion TBI device. SB-3CT (50 mg/kg in 10% dimethyl sulfoxide) was administered intraperitoneally at 30 min, 6 h, and 12 h after the TBI. Motor function (beam-balance/beam-walk tests) and spatial learning/memory (Morris water maze) were assessed on post-operative Days 1-5 and 11-15, respectively. Fluoro-Jade staining, immunofluorescence, and cresyl violet-staining were carried out for histopathological evaluation at 24 h, 72 h, and 15 days after TBI, respectively. It was shown that TBI can result in significant behavioral deficit induced by acute neurodegeneration, increased expression of cleaved caspase-3, and long-term neuronal loss. SB-3CT intervention via the current regime provides robust behavioral protection and hippocampal neurons preservation from the deleterious effects of TBI. Hence, the efficacy of SB-3CT on TBI prognosis could be ascertained. It is believed that the current study adds to the growing literature in identifying SB-3CT as a potential therapy for human brain injury.

High strength biocompatible PEG single-network hydrogels

A single-chain PEG hydrogel with extremely high strength was prepared via precise design and control over the molecular topology of the polymeric network.

Bio-inspired aquatic robotics by untethered piezohydroelastic actuation

This paper investigates fish-like aquatic robotics using flexible bimorphs made of macro-fiber composite (MFC) piezoelectric laminates for carangiform locomotion. In addition to noiseless and efficient actuation over a range of frequencies, geometric scalability, and simple design, bimorph propulsors made of MFCs offer a balance between the actuation force and velocity response for performance enhancement in bio-inspired swimming. The experimental component of the presented work focuses on the characterization of an elastically constrained MFC bimorph propulsor for thrust generation in quiescent water as well as the development of a robotic fish prototype combining a microcontroller and a printed-circuit-board amplifier to generate high actuation voltage for untethered locomotion. From the theoretical standpoint, a distributed-parameter electroelastic model including the hydrodynamic effects and actuator dynamics is coupled with the elongated-body theory for predicting the mean thrust in quiescent water. In-air and underwater experiments are performed to verify the incorporation of hydrodynamic effects in the linear actuation regime. For electroelastically nonlinear actuation levels, experimentally obtained underwater vibration response is coupled with the elongated-body theory to predict the thrust output. The measured mean thrust levels in quiescent water (on the order of ∼10 mN) compare favorably with thrust levels of biological fish. An untethered robotic fish prototype that employs a single bimorph fin (caudal fin) for straight swimming and turning motions is developed and tested in free locomotion. A swimming speed of 0.3 body-length/second (7.5 cm s⁻¹ swimming speed for 24.3 cm body length) is achieved at 5 Hz for a non-optimized main body-propulsor bimorph combination under a moderate actuation voltage level.

Randomized multicenter clinical trial of myofascial physical therapy in women with interstitial cystitis/painful bladder syndrome and pelvic floor tenderness

PURPOSE

We determined the efficacy and safety of pelvic floor myofascial physical therapy compared to global therapeutic massage in women with newly symptomatic interstitial cystitis/painful bladder syndrome.

MATERIALS AND METHODS

A randomized controlled trial of 10 scheduled treatments of myofascial physical therapy vs global therapeutic massage was performed at 11 clinical centers in North America. We recruited women with interstitial cystitis/painful bladder syndrome with demonstrable pelvic floor tenderness on physical examination and a limitation of no more than 3 years' symptom duration. The primary outcome was the proportion of responders defined as moderately improved or markedly improved in overall symptoms compared to baseline on a 7-point global response assessment scale. Secondary outcomes included ratings for pain, urgency and frequency, the O'Leary-Sant IC Symptom and Problem Index, and reports of adverse events. We compared response rates between treatment arms using the exact conditional version of the Mantel-Haenszel test to control for clustering by clinical center. For secondary efficacy outcomes cross-sectional descriptive statistics and changes from baseline were calculated.

RESULTS

A total of 81 women randomized to the 2 treatment groups had similar symptoms at baseline. The global response assessment response rate was 26% in the global therapeutic massage group and 59% in the myofascial physical therapy group (p=0.0012). Pain, urgency and frequency ratings, and O'Leary-Sant IC Symptom and Problem Index decreased in both groups during followup, and were not significantly different between the groups. Pain was the most common adverse event, occurring at similar rates in both groups. No serious adverse events were reported.

CONCLUSIONS

A significantly higher proportion of women with interstitial cystitis/painful bladder syndrome responded to treatment with myofascial physical therapy than to global therapeutic massage. Myofascial physical therapy may be a beneficial therapy in women with this syndrome.

Comparative impact on prostanoid biosynthesis of celecoxib and the novel nonsteroidal anti-inflammatory drug CG100649

Nonsteroidal anti-inflammatory drugs (NSAIDs) elevate cardiovascular risk by disrupting cyclooxygenase-2 (COX-2)-dependent biosynthesis of prostacyclin (PGI(2)). CG100649 is a novel NSAID proposed to inhibit both COX-2 and carbonic anhydrase (CA)-I/-II. We compared its impact on prostanoid biosynthesis with that of celecoxib, an NSAID purposefully designed to selectively inhibit COX-2. In a controlled, double-blind randomized trial, single oral doses of 2 or 8 mg CG100649, 200 mg celecoxib, or placebo were well tolerated by healthy volunteers (n = 23). Both CG100649 and celecoxib had the effect of depressing urinary excretion of 2,3-dinor-6-keto-PGF(1α) (PGI-M); the effect of CG100649 was dose-dependent and more sustained (up to 240 h after the dose) than that of celecoxib. Neither CG100649 nor celecoxib significantly inhibited COX-1-dependent prostanoid formation. CA inhibition was not detected after administration of CG100649, despite its partitioning asymmetrically into erythrocytes. CG100649 and celecoxib are both relatively selective inhibitors of COX-2, but they differ in duration of action. Whether they have similar impact on cardiovascular events remains to be determined.

Cryopreservation of tissue-engineered epithelial sheets in trehalose

Tissue-engineered epidermal membranes are useful for clinical wound healing. To facilitate these products in the clinic, optimized storage methods need to be developed. We studied the efficiency of extracellular trehalose at various concentrations for cryopreserving human tissue-engineered epidermal membranes compared with that of dimethyl-sulfoxide (DMSO) used by most organ banks for cryopreserving skin grafts and artificial skin substitutes. Keratinocyte (KC) viability, proliferation and marker expression following cryopreservation in trehalose were examined with similar results to those using DMSO. Trehalose concentration (0.4m) was optimized according to the described cellular activities following cryopreservation. Artificial epidermal substitutes were then cryopreserved in trehalose at the optimized concentration. Cell viability, growth factor secretion and wound healing properties of cryopreserved artificial epidermal substitutes using nude mice were examined and compared with those of DMSO cryopreservation. Cryopreservation with trehalose enhanced human KC viability in suspension and artificial skin substitutes. In addition, trehalose cryopreservation provided fast recovery of EGF and TGF-β1 secretion by KCs after thawing. When transplanted into nude mice, trehalose-cryopreserved artificial skin repaired skin defects in a similar manner to that of a non-cryopreserved control. Moreover, trehalose-cryopreserved artificial skin resulted in engraftment and wound closure that was significantly enhanced compared with that of DMSO-cryopreserved epidermal membranes. The results indicate that the use of trehalose improves cryopreservation of tissue-engineered epithelial sheets.

Differentiation of adipose-derived stem cells into contractile smooth muscle cells induced by transforming growth factor-beta1 and bone morphogenetic protein-4

Smooth muscle cells (SMCs) play an essential role in maintaining the structural and functional integrity of blood vessel and thus is a critical element for blood vessel construction via tissue engineering approach. Adipose-derived stem cells (ASCs) represent a reliable source of mesenchymal stem cells with multidifferentiation potential. In this study, the feasibility of differentiation of human ASCs (hASCs) into cells with phenotypic and functional properties of SMCs was explored. hASCs isolated from human lipoaspirate were expanded to passage 5 and then induced with administration of transforming growth factor-beta1 (TGF-beta1) and bone morphogenetic protein-4 (BMP4) either alone or in combination with culture medium. Expression of SMC-related markers including alpha-SM actin (alpha-SMA, SM22alpha, calponin, and SM myosin heavy chain) were detected by immunofluorescent staining, reverse transcription (RT)-polymerase chain reaction, and western blot analysis. It was found that only under the circumstance of a combined stimulation with TGF-beta1 and BMP4, both early and mid markers (alpha-SMA, SM22alpha, calponin) as well as a late marker (SM myosin heavy chain) of SMC differentiation were identified to similar levels as those in human umbilical artery SMCs. More importantly, these SM differentiated cells showed the function of contracting collagen matrix lattice when they were entrapped inside. The contractile function of differentiated hASCs was further enhanced by direct exposure to 60 mM KCl, consistent with what occurred in human umbilical artery SMCs. These results provide evidence that ASCs possess the potential to differentiate into contractile SM-like cells when stimulated by TGF-beta1 and BMP4 together. SMCs differentiated from hASCs may provide an abundant source as seed cells for blood vessel engineering.

Comparative investigation of viability, metabolism and osteogenic capability of tissue-engineered bone preserved in sealed osteogenic media at 37 °C and 4 °C

Preservation of tissue-engineered (TE) bone is one of the key problems needed to be solved for its clinic application and industrialization. Traditional cryopreservation has been restricted because of the damages caused by ice formation and solution. Hypothermic preservation at 4 °C has been widely used for the preservation of transplanted organ despite potential negative effects on viability of cells and tissue. 37 °C is the best temperature for maintaining cellular bioactivities. However, 37 °C also has a potential negative effect on preserved cells due to consumption of nutrients and accumulation of by-products. No studies have reported which temperature is more suitable for the preservation of TE bone constructs. The current study explored the feasibility of preservation of TE bone constructs in sealed osteogenic media at 37 °C and 4 °C. Human bone marrow stromal cells (hBMSCs) were seeded into partially demineralized bone matrix (pDBM) scaffolds and cultured for 7 days to form TE bone constructs. The constructs were preserved in sealed osteogenic media at either 37 °C or 4 °C for 5, 7, 9 and 11 days, respectively. Growth kinetics, viability, metabolism and osteogenic capability were evaluated to explore the feasibility of preservation at 37 °C and 4 °C. The constructs cultured in osteogenic media at humidified 37 °C/5%CO2 served as the positive control. The results demonstrated that all the constructs preserved at 4 °C showed negative osteogenic capability at all time points with a much lower level of growth kinetics, viability and metabolism compared to the positive control. However, the constructs preserved at 37 °C showed good osteogenic capability within 7 days with a certain level of growth kinetics, viability and metabolism, although an obvious decrease in osteogenic capability was observed in the constructs preserved at 37 °C over 9 days. These results indicate that the preservation of TE bone constructs is feasible at 37 °C within 7 days in sealed osteogenic media.

Incorporation of tripolyphosphate nanoparticles into fibrous poly(lactide-co-glycolide) scaffolds for tissue engineering

Poly(lactide-co-glycolide) (PLGA) has been widely used for scaffolding materials in tissue engineering. It degrades mainly via hydrolysis of the ester bonds into lactic acid and glycolic acid leading to the decrease in pH of the surrounding microenvironment. The current study was designed to quickly neutralize the acidic degradation products of PLGA fibrous scaffolds by incorporating tripolyphosphate (TPP) nanoparticles into PLGA fibers. A homogeneous mixture of PLGA and TPP was first obtained by water-in-oil emulsion-dispersion followed by freeze-drying. The dried blend was melt-spun to yield fibers which were processed into scaffolds and subsequently immersed into phosphate-buffered saline (PBS) to verify the degradation properties. The pH of the saline was monitored for a duration of 80 days. The amount of TPP was optimized to obtain a PLGA based scaffolds without acidic degradation problems. Cellular compatibility of the modified and pristine scaffolds was evaluated using rabbit adipose-derived stem cells (rASCs). It was shown that TPP particles within the fibers were roughly 100nm in diameter and mainly located inside fibers instead of on the superficial layer. The acidic degradation of PT-16 and PT-64 (PT-X is termed when the monomer molar ratio of TPP to PLGA was 1:X) was significantly improved as the pH values of their respective solutions were maintained in a well neutralized state during the degradation. PT-64 and PT-16 scaffolds could well support the attachment and proliferation of rASCs. Hence, the incorporation of TPP nanoparticles via an emulsion-dispersion method could be an effective strategy to improve/adjust the acidic degradation of PLGA and further pave the way for clinical applications of such polyesters.