Twenty-five years of recombinant human growth factors rhPDGF-BB and rhBMP-2 in oral hard and soft tissue regeneration.

Contemporary oral tissue engineering strategies involve recombinant human growth factor approaches to stimulate diverse cellular processes including cell differentiation, migration, recruitment, and proliferation at grafted areas. Recombinant human growth factor applications in oral hard and soft tissue regeneration have been progressively researched over the last 25 years. Growth factor-mediated surgical approaches aim to accelerate healing, tissue reconstruction, and patient recovery. Thus, regenerative approaches involving growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and recombinant human bone morphogenetic proteins (rhBMPs) have shown certain advantages over invasive traditional surgical approaches in severe hard and soft tissue defects. Several clinical studies assessed the outcomes of rhBMP-2 in diverse clinical applications for implant site development and bone augmentation. Current evidence regarding the clinical benefits of rhBMP-2 compared to conventional therapies is inconclusive. Nevertheless, it seems that rhBMP-2 can promote faster wound healing processes and enhance de novo bone formation, which may be particularly favorable in patients with compromised bone healing capacity or limited donor sites. rhPDGF-BB has been extensively applied for periodontal regenerative procedures and for the treatment of gingival recessions, showing consistent and positive outcomes. Nevertheless, current evidence regarding its benefits at implant and edentulous sites is limited. The present review explores and depicts the current applications, outcomes, and evidence-based clinical recommendations of rhPDGF-BB and rhBMPs for oral tissue regeneration

Advanced technologies to target cardiac cell fate plasticity for heart regeneration

The adult human heart can only adapt to heart diseases by starting a myocardial remodeling process to compensate for the loss of functional cardiomyocytes, which ultimately develop into heart failure. In recent decades, the evolution of new strategies to regenerate the injured myocardium based on cellular reprogramming represents a revolutionary new paradigm for cardiac repair by targeting some key signaling molecules governing cardiac cell fate plasticity. While the indirect reprogramming routes require an in vitro engineered 3D tissue to be transplanted in vivo, the direct cardiac reprogramming would allow the administration of reprogramming factors directly in situ, thus holding great potential as in vivo treatment for clinical applications. In this framework, cellular reprogramming in partnership with nanotechnologies and bioengineering will offer new perspectives in the field of cardiovascular research for disease modeling, drug screening, and tissue engineering applications. In this review, we will summarize the recent progress in developing innovative therapeutic strategies based on manipulating cardiac cell fate plasticity in combination with bioengineering and nanotechnology-based approaches for targeting the failing heart

A Current Overview of Materials and Strategies for Potential Use in Maxillofacial Tissue Regeneration

Tissue regeneration is rapidly evolving to treat anomalies in the entire human body. The production of biodegradable, customizable scaffolds to achieve this clinical aim is dependent on the interdisciplinary collaboration among clinicians, bioengineers and materials scientists. While bone grafts and varying reconstructive procedures have been traditionally used for maxillofacial defects, the goal of this review is to provide insight on all materials involved in the progressing utilization of the tissue engineering approach to yield successful treatment outcomes for both hard and soft tissues. In vitro and in vivo studies that have demonstrated the restoration of bone and cartilage tissue with different scaffold material types, stem cells and growth factors show promise in regenerative treatment interventions for maxillofacial defects. The repair of the temporomandibular joint (TMJ) disc and mandibular bone were discussed extensively in the report, supported by evidence of regeneration of the same tissue types in different medical capacities. Furthermore, in addition to the thorough explanation of polymeric, ceramic, and composite scaffolds, this review includes the application of biodegradable metallic scaffolds for regeneration of hard tissue. The purpose of compiling all the relevant information in this review is to lay the foundation for future investigation in materials used in scaffold synthesis in the realm of oral and maxillofacial surgery

Mesenchymal Progenitor Cells and Their Orthopedic Applications: Forging a Path towards Clinical Trials

Mesenchymal progenitor cells (MPCs) are nonhematopoietic multipotent cells capable of differentiating into mesenchymal and nonmesenchymal lineages. While they can be isolated from various tissues, MPCs isolated from the bone marrow are best characterized. These cells represent a subset of bone marrow stromal cells (BMSCs) which, in addition to their differentiation potential, are critical in supporting proliferation and differentiation of hematopoietic cells. They are of clinical interest because they can be easily isolated from bone marrow aspirates and expanded in vitro with minimal donor site morbidity. The BMSCs are also capable of altering disease pathophysiology by secreting modulating factors in a paracrine manner. Thus, engineering such cells to maximize therapeutic potential has been the focus of cell/gene therapy to date. Here, we discuss the path towards the development of clinical trials utilizing BMSCs for orthopaedic applications. Specifically, we will review the use of BMSCs in repairing critical-sized defects, fracture nonunions, cartilage and tendon injuries, as well as in metabolic bone diseases and osteonecrosis. A review of www.ClinicalTrials.gov of the United States National Institute of Health was performed, and ongoing clinical trials will be discussed in addition to the sentinel preclinical studies that paved the way for human investigations

Recent Advancements in Regenerative Dentistry: A Review

Although human mouth benefits from remarkable mechanical properties, it is very susceptible to traumatic damages, exposure to microbial attacks, and congenital maladies. Since the human dentition plays a crucial role in mastication, phonation and esthetics, finding promising and more efficient strategies to reestablish its functionality in the event of disruption has been important. Dating back to antiquity, conventional dentistry has been offering evacuation, restoration, and replacement of the diseased dental tissue. However, due to the limited ability and short lifespan of traditional restorative solutions, scientists have taken advantage of current advancements in medicine to create better solutions for the oral health field and have coined it “regenerative dentistry.” This new field takes advantage of the recent innovations in stem cell research, cellular and molecular biology, tissue engineering, and materials science etc. In this review, the recently known resources and approaches used for regeneration of dental and oral tissues were evaluated using the databases of Scopus and Web of Science. Scientists have used a wide range of biomaterials and scaffolds (artificial and natural), genes (with viral and non-viral vectors), stem cells (isolated from deciduous teeth, dental pulp, periodontal ligament, adipose tissue, salivary glands, and dental follicle) and growth factors (used for stimulating cell differentiation) in order to apply tissue engineering approaches to dentistry. Although they have been successful in preclinical and clinical partial regeneration of dental tissues, whole-tooth engineering still seems to be far-fetched, unless certain shortcomings are addressed

Recent Advances and Current Developments in Tissue Scaffolding

A bio-scaffold can be broadly termed as a structure used to substitute an organ either permanently or temporarily to restore functionality. The material that can be used varies with the application intended. Tissue engineering is one such application demanding certain requirements to be met before it is applied. One of the applications in tissue engineering is the tissue scaffold, which provides either a permanent or temporary support to the damaged tissues/organ until the functionalities are restored. A biomaterial can exhibit specific interactions with cells that will lead to stereotyped responses. The use of a particular material and morphology depends on various factors such as osteoinduction, osteoconduction, angiogenesis, growth rates of cells and degradation rate of the material in case of temporary scaffolds, etc. The current work reviews the state of art in tissue scaffolds and focuses on permanent scaffold materials and applications with a brief overview of temporary scaffold materials and their disadvantages

Genome editing technologies to fight infectious diseases

Genome editing by programmable nucleases represents a promising tool that could be exploited to develop new therapeutic strategies to fight infectious diseases. These nucleases, such as zinc-finger nucleases, transcription activator-like effector nucleases, clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) and homing endonucleases, are molecular scissors that can be targeted at predetermined loci in order to modify the genome sequence of an organism. Areas covered: By perturbing genomic DNA at predetermined loci, programmable nucleases can be used as antiviral and antimicrobial treatment. This approach includes targeting of essential viral genes or viral sequences able, once mutated, to inhibit viral replication; repurposing of CRISPR-Cas9 system for lethal self-targeting of bacteria; targeting antibiotic-resistance and virulence genes in bacteria, fungi, and parasites; engineering arthropod vectors to prevent vector-borne infections. Expert commentary: While progress has been done in demonstrating the feasibility of using genome editing as antimicrobial strategy, there are still many hurdles to overcome, such as the risk of off-target mutations, the raising of escape mutants, and the inefficiency of delivery methods, before translating results from preclinical studies into clinical applications

Introductory editorial: drug-eluting stents or drug-eluting grafts? Insights from proteomic analysis

No abstract available

Introducing monitoring and automation in cartilage tissue engineering, toward controlled clinical translation

The clinical application of tissue engineered products requires to be tightly connected with the possibility to control the process, assess graft quality and define suitable release criteria for implantation. The aim of this work is to establish techniques to standardize and control the in vitro engineering of cartilage grafts. The work is organized in three sub-projects: first a method to predict cell proliferation capacity was studied, then an in line technique to monitor the draft during in vitro culture was developed and, finally, a culture system for the reproducible production of engineered cartilage was designed and validated. Real-time measurements of human chondrocyte heat production during in vitro proliferation. Isothermal microcalorimetry (IMC) is an on-line, non-destructive and high resolution technique. In this project we aimed to verify the possibility to apply IMC to monitor the metabolic activity of primary human articular chondrocytes (HAC) during their in vitro proliferation. Indeed, currently, many clinically available cell therapy products for the repair of cartilage lesions involve a process of in vitro cell expansion. Establishing a model system able to predict the efficiency of this lengthy, labor-intensive, and challenging to standardize step could have a great potential impact on the manufacturing process. In this study an optimized experimental set up was first established, to reproducible acquire heat flow data; then it was demonstrated that the HAC proliferation within the IMC-based model was similar to proliferation under standard culture conditions, verifying its relevance for simulating the typical cell culture application. Finally, based on the results from 12 independent donors, the possible predictive potential of this technique was assessed. Online monitoring of oxygen as a non-destructive method to quantify cells in engineered 3D tissue constructs. This project aimed at assessing a technique to monitor graft quality during production and/or at release. A quantitative method to monitor the cells number in a 3D construct, based on the on-line measurement of the oxygen consumption in a perfusion based bioreactor system was developed. Oxygen levels dissolved in the medium were monitored on line, by two chemo-optic flow-through micro-oxygen sensors connected at the inlet and the outlet of the bioreactor scaffold chamber. A destructive DNA assay served to quantify the number of cells at the end of the culture. Thus the oxygen consumption per cell could be calculated as the oxygen drop across the perfused constructs at the end of the culture period and the number of cells quantified by DNA. The method developed would allow to non-invasively monitoring in real time the number of chondrocytes on the scaffold. Bioreactor based engineering of large-scale human cartilage grafts for joint resurfacing. The aim of this project was to upscale the size of engineered human cartilage grafts. The main aim of this project consisted in the design and prototyping of a direct perfusion bioreactor system, based on fluidodynamic models (realized in collaboration with the Institute for Bioengineering of Catalonia, Spain), able to guarantee homogeneous seeding and culture conditions trough the entire scaffold surface. The system was then validated and the capability to reproducibly support the process of tissue development was tested by histological, biochemical and biomechanical assays. Within the same project the automation of the designed scaled up bioreactor system, thought as a stand alone system, was proposed. A prototype was realized in collaboration with Applikon Biotechnology BV, The Netherlands. The developed system allows to achieve within a closed environment both cell seeding and culture, controlling some important environmental parameters (e.g. temperature, CO2 and O2 tension), coordinating the medium flow and tracking culture development. The system represents a relevant step toward process automation in tissue engineering and, as previously discussed, enhancing the automation level is an important requirement in order to move towards standardized protocols of graft generation for the clinical practice. These techniques will be critical towards a controlled and standardized procedure for clinical implementation of tissue engineering products and will provide the basis for controlled in vitro studies on cartilage development. Indeed the resulting methods have already been integrated in a streamlined, controlled, bioreactor based protocol for the in vitro production of up scaled engineered cartilage drafts. Moreover the techniques described will serve as the foundation for a recently approved Collaborative Project funded by the European Union, having the goal to produce cartilage tissue grafts. In order to reach this goal the research based technologies and processes described in this dissertation will be adapted for GMP compliance and conformance to regulatory guidelines for the production of engineered tissues for clinical use, which will be tested in a clinical trial