In vitro and in vivo behaviour of biodegradable and injectable PLA/PGA copolymers related to different matrices

Agarose Gel: An Overview of the Dermal Filler and a Clinical Experience With 700 Patients

Background

Dermal fillers currently in the market have several advantages and disadvantages over each other. Agarose gel (AG) is a unique material due to its special rheological characteristics and gel-forming capability.

Objectives

The authors aimed to share their clinical experience on AG for a variety of facial augmentation procedures and its long-term results.

Methods

The study population consisted of 700 patients (532 females; 168 males) aged 18 to 52 years. Follow-up visits were at 1, 3, 6, 12, and 24 months after the injections. Patient satisfaction was evaluated on a scale from 0 to 10 using a survey and clinical improvement was evaluated using the Global Aesthetic Improvement Scale (GAIS) by 2 independent plastic surgeons before the injection and at 1-year follow-up.

Results

Eighty-two percent of the patients scored 1 or 2 (exceptional or great improvement) on GAIS. Eighty-five percent of the patients scored 8 or above (very satisfied). Most patients experienced at least 80% persistence of effect at 1-year follow-up.

Conclusions

AG appears to be suitable for a variety of facial augmentation and contouring applications, as it is safe and has long-lasting favorable cosmetic efficacy.

Level of Evidence 3

Vegetable hierarchical structures as template for bone regeneration: New bio-ceramization process for the development of a bone scaffold applied to an experimental sheep model

Long bone defects still represent a major clinical challenge in orthopedics, with the inherent loss of function considerably impairing the quality of life of the affected patients. Thus, the purpose of this study was to assess the safety and potential of bone regeneration offered by a load-bearing scaffold characterized by unique hierarchical architecture and high strength, with active surface facilitating new bone penetration and osseointegration in critical size bone defects. The results of this study showed the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of new wood-derived bone scaffolds, further improved by surface functionalization, with good biological and mechanical properties leading to successful treatment of critical size bone defects in the sheep model. Future studies are needed to evaluate if these scaffolds prototypes, as either biomaterial alone or in combination with augmentation strategies, may represent an optimal solution to enhance bone regeneration in humans.

New bio-ceramization processes applied to vegetable hierarchical structures for bone regeneration: an experimental model in sheep

Bone loss is still a major problem in orthopedics. The purpose of this experimental study is to evaluate the safety and regenerative potential of a new scaffold based on a bio-ceramization process for bone regeneration in long diaphyseal defects in a sheep model. The scaffold was obtained by transformation of wood pieces into porous biomorphic silicon carbide (BioSiC®). The process enabled the maintenance of the original wood microstructure, thus exhibiting hierarchically organized porosity and high mechanical strength. To improve cell adhesion and osseointegration, the external surface of the hollow cylinder was made more bioactive by electrodeposition of a uniform layer of collagen fibers that were mineralized with biomimetic hydroxyapatite, whereas the internal part was filled with a bio-hybrid HA/collagen composite. The final scaffold was then implanted in the metatarsus of 15 crossbred (Merinos-Sarda) adult sheep, divided into 3 groups: scaffold alone, scaffold with platelet-rich plasma (PRP) augmentation, and scaffold with bone marrow stromal cells (BMSCs) added during implantation. Radiological analysis was performed at 4, 8, 12 weeks, and 4 months, when animals were sacrificed for the final radiological, histological, and histomorphometric evaluation. In all tested treatments, these analyses highlighted the presence of newly formed bone at the bone scaffolds' interface. Although a lack of substantial effect of PRP was demonstrated, the scaffold+BMSC augmentation showed the highest value of bone-to-implant contact and new bone growth inside the scaffold. The findings of this study suggest the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of wood-derived bone scaffolds, and document a suitable augmentation procedure in enhancing bone regeneration, particularly when combined with BMSCs.

Microstructured titanium regulates interleukin production by osteoblasts, an effect modulated by exogenous BMP-2

Microtextured implant surfaces increase osteoblast differentiation in vitro and enhance bone-to-implant contact in vivo and clinically. These implants may be used in combination with recombinant human bone morphogenetic protein 2 (rhBMP-2) to enhance peri-implant bone formation. However, the effect of surface modifications alone or in combination with rhBMP-2 on the osteoblast-produced inflammatory microenvironment is unknown. MG63 cells were cultured on tissue culture polystyrene or titanium substrates: smooth pretreated (PT, Ra=0.2μm), sandblasted/acid-etched (SLA, Ra=3.2μm) or hydrophilic-SLA (modSLA). Expression and protein production of pro-inflammatory interleukins (IL1b, IL6, IL8, IL17) and anti-inflammatory interleukins (IL10) were measured in cells with or without rhBMP-2. To determine which BMP signaling pathways were involved, cultures were incubated with BMP pathway inhibitors to blockSmad (dorsomorphin), TAB/TAK1 ((5Z)-7-oxozeaenol) or PKA (H-8) signaling. Culture on rough SLA and modSLA surfaces decreased pro-inflammatory interleukins and increased anti-inflammatory IL10. This effect was negated in cells treated with rhBMP-2, which caused an increase in pro-inflammatory interleukins and a decrease in anti-inflammatory interleukins through TAB/TAK signaling. The results suggest that surface microtexture modulates the inflammatory process during osseointegration, an effect that may enhance healing. However, rhBMP-2 in combination with microtextured titanium implants can influence the effect of cells on these surfaces, and may adversely affect cells involved in osseointegration.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed. These materials were investigated for the repair of cartilage, bone, adipose tissue, intervertebral disc, neural, and cardiac tissue. Papers from the last ten years were considered, with a particular focus on the advances of the last five years. A critical discussion is centered on new perspectives and challenges in the regeneration of specific tissues, with the aim of highlighting the limits of current systems and possible future advancements.

Agarose gel as biomaterial or scaffold for implantation surgery: characterization, histological and histomorphometric study on soft tissue response

Maxillofacial, orthopedic, oral, and plastic surgery require materials for tissue augmentation, guided regeneration, and tissue engineering approaches. In this study, the aim was to develop and characterize a new extrudable hydrogel, based on agarose gel (AG; 1.5% wt) and to evaluate the local effects after subcutaneous implantation in comparison with collagen and hyaluronic acid. AG chemical-physical properties were ascertained through Fourier transform infrared (FT-IR) spectroscopy and rheological analysis. In vivo subcutaneous implants were performed, and histological and histomorphometric evaluations were done at 1, 4, 12, and 16 weeks. FT-IR confirmed that spectroscopic properties were the same for the baseline agarose and rheological characterization established that AG is a weak hydrogel. Subcutaneous AG implants induced new vessels and fibrous tissue formation rich in neutrophils; the capsule thickness around AG increased until the 12th week but remained thinner than those around hyaluronic acid and collagen. At 16 weeks, the thickness of the capsule significantly decreased around all materials. This study confirmed that 1.5% wt AG possesses some of the most important features of the ideal biocompatible material: safety, effectiveness, costless, and easily obtained with specific chemical and geometrical characters; the AG can represent a finely controllable and biodegradable polymeric system for cells and drug delivery applications.

Preparation, physicochemical characterization and cytotoxicity in vitro of gemcitabine-loaded PEG-PDLLA nanovesicles

AIM: To investigate the preparation, physicochemical characterization and cytotoxicity in vitro of Gemcitabine-loaded poly(ethylene glycol)-block-poly(D,L-lactide) (PEG-PDLLA) nanovesicles.

METHODS: The nanovesicle carriers were prepared from the amphiphilic block copolymer of PEG-PDLLA by a double emulsion technique, and gemcitabine was used as the model drug. The morphology of the nanovesicles was determined by scanning and transmission electron microscopy, and the drug content, drug entrapment and drug-release curve in vitro were detected by UV-Vis-NIR spectrophotometry. Cytotoxicity in the human pancreatic cancer cell line SW1990 was tested by 3-(4,5-dimethyl) ethiazole (MTT) assay.

RESULTS: The gemcitabine-loaded nanovesicles were hollow nanospheres with a mean size of 200.6 nm, drug loading of 4.14% and drug embedding ratio of 20.54%. The nanovesicles showed excellent controlled release that was characterized by a fast initial release during the first 72 h, followed by a slower and continuous release. The MTT assay demonstrated that gemcitabine-loaded nanovesicles exhibited dose-dependent and time-delayed cytotoxicity in the human pancreatic cancer cell line SW1990.

CONCLUSION: Gemcitabine-loaded PEG-PDLLA nanovesicles prepared by a double emulsion technique exhibited good performance for controlled drug release, and had similar cytotoxic activity to free gemcitabine.

Bone regeneration potential of a soybean-based filler: experimental study in a rabbit cancellous bone defects

Autologous and allogenic bone grafts are considered as materials of choice for bone reconstructive surgery, but limited availability, risks of transmittable diseases and inconsistent clinical performances have prompted the development of alternative biomaterials. The present work compares the bone regeneration potential of a soybean based bone filler (SB bone filler) in comparison to a commercial 50:50 poly(D: ,L: lactide-glycolide)-based bone graft (Fisiograft((R)) gel) when implanted into a critical size defect (6-mm diameter, 10-mm length) in rabbit distal femurs. The histomorphometric and microhardness analyses of femoral condyles 4, 8, 16 and 24 weeks after surgery showed that no significant difference was found in the percentage of both bone repair and bone in-growth in the external, medium and inner defect areas. The SB filler-treated defects showed significantly higher outer bone formation and microhardness results at 24 weeks than Fisiograft((R)) gel (P < 0.05). Soybean-based biomaterials clearly promoted bone repair through a mechanism of action that is likely to involve both the scaffolding role of the biomaterial for osteoblasts and the induction of their differentiation.