Towards bone regeneration: Understanding the nucleating ability of proline-rich peptides in biomineralisation.

Obtaining rapid mineralisation is a challenge in current bone graft materials, which has been attributed to the difficulty of guiding the biological processes towards osteogenesis. Amelogenin, a key protein in enamel formation, inspired the design of two intrinsically disordered peptides (P2 and P6) that enhance in vivo bone formation, but the process is not fully understood. In this study, we have elucidated the mechanism by which these peptides induce improved mineralisation. Our molecular dynamics analysis demonstrated that in an aqueous environment, P2 and P6 fold to interact with the surrounding Ca2+, PO43- and OH- ions, which can lead to apatite nucleation. Although P2 has a less stable backbone, it folds to a stable structure that allows for the nucleation of larger calcium phosphate aggregates than P6. These results were validated experimentally in a concentrated simulated body fluid solution, where the peptide solutions accelerated the mineralisation process compared to the control and yielded mineral structures mimicking the amorphous calcium phosphate crystals that can be found in lamella bone. A pH drop for the peptide groups suggests depletion of calcium and phosphate, a prerequisite for intrinsic osteoinduction, while S/TEM and SEM suggested that the peptide regulated the mineral nucleation into lamella flakes. Evidently, the peptides accelerate and guide mineral formation, elucidating the mechanism for how these peptides can improve the efficacy of P2 or P6 containing devices for bone regeneration. The work also demonstrates how experimental mineralisation study coupled with molecular dynamics is a valid method for understanding and predicting in vivo performance prior to animal trials.

Biomaterials and Cell Therapy Combination in Central Nervous System Treatments.

Current pharmacological and surgical therapies for the central nervous system (CNS) show a limited capacity to reduce the damage progression; that together with the intrinsic limited capability of the CNS to regenerate greatly reduces the hopes of recovery. Among all the therapies proposed, the tissue engineering strategies supplemented with therapeutic stem cells remain the most promising. Neural tissue engineering strategies are based on the development of devices presenting optimal physical, chemical, and mechanical properties which, once inserted in the injured site, can support therapeutic cells, limiting the effect of a hostile environment and supporting regenerative processes. Thus, this review focuses on the employment of hydrogel and nanofibrous scaffolds supplemented with stem cells as promising therapeutic tools for the central and peripheral nervous systems in preclinical and clinical applications.

A composite, off-the-shelf osteoinductive material for large, vascularized bone flap prefabrication.

We previously described an immortalized, genetically-engineered human Mesenchymal stromal cell line to generate BMP2-enriched Chondrogenic Matrices (MB-CM), which after devitalization and storage could efficiently induce ectopic bone tissue by endochondral ossification. In order to increase the efficiency of MB-CM utilization towards engineering scaled-up bone structures, here we hypothesized that MB-CM can retain osteoinductive properties when combined with an osteoconductive material. We first tested different volumetric ratios of MB-CM:SmartBone® (as clinically used, osteoconductive reference material) and assessed the bone formation capacity of the resulting composites following ectopic mouse implantation. After 8 weeks, as little as 25% of MB-CM was sufficient to induce bone formation and fusion across SmartBone® granules, generating large interconnected bony structures. The same composite percentage was then further assessed in a scaled-up model, namely within an axially-vascularized, confined, ectopically prefabricated flap (0.8 cm3) in rats. The material efficiently induced the formation of new bone (31% of the cross-sectional area after 8 weeks), including bone marrow and vascular elements, throughout the flap volume. Our findings outline a strategy for efficient use of MB-CM as part of a composite material, thereby reducing the amount required to fill large spaces and enabling utilization in critically sized grafts, to address challenging clinical scenarios in bone reconstruction. STATEMENT OF SIGNIFICANCE: Most bone repair strategies rely either on osteconductive properties of ceramics and devitalized bone, or osteoinductive properties of growth factors and extracellular matrices (ECM). Here we designed a composite material made of a clinically accepted osteoconductive material and an off-the-shelf tissue engineered human cartilage ECM with strong osteoinductive properties. We showed that low amount of osteoinductive ECM potentiated host cells recruitment to form large vascularized bone structures in two different animal models, one being a challenging prefabricated bone-flap model targeting challenging clinical bone repair. Overall, this study highlights the use of a promising human off-the-shelf material for accelerated healing towards clinical applications.

Biomaterial-Mediated Factor Delivery for Spinal Cord Injury Treatment.

Spinal cord injury (SCI) is an injurious process that begins with immediate physical damage to the spinal cord and associated tissues during an acute traumatic event. However, the tissue damage expands in both intensity and volume in the subsequent subacute phase. At this stage, numerous events exacerbate the pathological condition, and therein lies the main cause of post-traumatic neural degeneration, which then ends with the chronic phase. In recent years, therapeutic interventions addressing different neurodegenerative mechanisms have been proposed, but have met with limited success when translated into clinical settings. The underlying reasons for this are that the pathogenesis of SCI is a continued multifactorial disease, and the treatment of only one factor is not sufficient to curb neural degeneration and resulting paralysis. Recent advances have led to the development of biomaterials aiming to promote in situ combinatorial strategies using drugs/biomolecules to achieve a maximized multitarget approach. This review provides an overview of single and combinatorial regenerative-factor-based treatments as well as potential delivery options to treat SCIs.

Design and clinical application of injectable hydrogels for musculoskeletal therapy.

Musculoskeletal defects are an enormous healthcare burden and source of pain and disability for individuals. With an aging population, the proportion of individuals living with these medical indications will increase. Simultaneously, there is pressure on healthcare providers to source efficient solutions, which are cheaper and less invasive than conventional technology. This has led to an increased research focus on hydrogels as highly biocompatible biomaterials that can be delivered through minimally invasive procedures. This review will discuss how hydrogels can be designed for clinical translation, particularly in the context of the new European Medical Device Regulation (MDR). We will then do a deep dive into the clinically used hydrogel solutions that have been commercially approved or have undergone clinical trials in Europe or the United States. We will discuss the therapeutic mechanism and limitations of these products. Due to the vast application areas of hydrogels, this work focuses only on treatments of cartilage, bone, and the nucleus pulposus. Lastly, the main steps toward clinical translation of hydrogels as medical devices are outlined. We suggest a framework for how academics can assist small and medium MedTech enterprises conducting the initial clinical investigation and post-market clinical follow-up required in the MDR. It is evident that the successful translation of hydrogels is governed by acquiring high-quality pre-clinical and clinical data confirming the device mechanism of action and safety.

Biohybrid Bovine Bone Matrix for Controlled Release of Mesenchymal Stem/Stromal Cell Lyosecretome: A Device for Bone Regeneration.

SmartBone® (SB) is a biohybrid bone substitute advantageously proposed as a class III medical device for bone regeneration in reconstructive surgeries (oral, maxillofacial, orthopedic, and oncology). In the present study, a new strategy to improve SB osteoinductivity was developed. SB scaffolds were loaded with lyosecretome, a freeze-dried formulation of mesenchymal stem cell (MSC)-secretome, containing proteins and extracellular vesicles (EVs). Lyosecretome-loaded SB scaffolds (SBlyo) were prepared using an absorption method. A burst release of proteins and EVs (38% and 50% after 30 min, respectively) was observed, and then proteins were released more slowly with respect to EVs, most likely because they more strongly adsorbed onto the SB surface. In vitro tests were conducted using adipose tissue-derived stromal vascular fraction (SVF) plated on SB or SBlyo. After 14 days, significant cell proliferation improvement was observed on SBlyo with respect to SB, where cells filled the cavities between the native trabeculae. On SB, on the other hand, the process was still present, but tissue formation was less organized at 60 days. On both scaffolds, cells differentiated into osteoblasts and were able to mineralize after 60 days. Nonetheless, SBlyo showed a higher expression of osteoblast markers and a higher quantity of newly formed trabeculae than SB alone. The quantification analysis of the newly formed mineralized tissue and the immunohistochemical studies demonstrated that SBlyo induces bone formation more effectively. This osteoinductive effect is likely due to the osteogenic factors present in the lyosecretome, such as fibronectin, alpha-2-macroglobulin, apolipoprotein A, and TGF-ß.

Marine Anticancer Agents: An Overview with a Particular Focus on Their Chemical Classes.

The marine environment is a rich source of biologically active molecules for the treatment of human diseases, especially cancer. The adaptation to unique environmental conditions led marine organisms to evolve different pathways than their terrestrial counterparts, thus producing unique chemicals with a broad diversity and complexity. So far, more than 36,000 compounds have been isolated from marine micro- and macro-organisms including but not limited to fungi, bacteria, microalgae, macroalgae, sponges, corals, mollusks and tunicates, with hundreds of new marine natural products (MNPs) being discovered every year. Marine-based pharmaceuticals have started to impact modern pharmacology and different anti-cancer drugs derived from marine compounds have been approved for clinical use, such as: cytarabine, vidarabine, nelarabine (prodrug of ara-G), fludarabine phosphate (pro-drug of ara-A), trabectedin, eribulin mesylate, brentuximab vedotin, polatuzumab vedotin, enfortumab vedotin, belantamab mafodotin, plitidepsin, and lurbinectedin. This review focuses on the bioactive molecules derived from the marine environment with anticancer activity, discussing their families, origin, structural features and therapeutic use.

In vivo drug delivery applications of nanogels: a review.

In recent years, nanogels have emerged as promising drug delivery vehicles; their ability in holding active molecules, macromolecules and drugs, together with the capability to respond to external stimuli, makes them a suitable tool for a wide range of applications. These features allow nanogels to be exploited against many challenges of nanomedicine associated with different kinds of pathologies which require the use of specific drug delivery systems. In this review our aim is to give the reader an overview of the diseases that can be treated with nanogels as drug delivery systems, such as cancer, CNS disorders, cardiovascular diseases, wound healing and other diseases of human body. For all of these pathologies, biological in vivo assays can be found in the literature and in this work. We focus on the peculiarities of these nanogels, highlighting their features and their advantages in respect to conventional treatments.

The Few Who Made It: Commercially and Clinically Successful Innovative Bone Grafts.

Bone reconstruction techniques are mainly based on the use of tissue grafts and artificial scaffolds. The former presents well-known limitations, such as restricted graft availability and donor site morbidity, while the latter commonly results in poor graft integration and fixation in the bone, which leads to the unbalanced distribution of loads, impaired bone formation, increased pain perception, and risk of fracture, ultimately leading to recurrent surgeries. In the past decade, research efforts have been focused on the development of innovative bone substitutes that not only provide immediate mechanical support, but also ensure appropriate graft anchoring by, for example, promoting de novo bone tissue formation. From the countless studies that aimed in this direction, only few have made the big jump from the benchtop to the bedside, whilst most have perished along the challenging path of clinical translation. Herein, we describe some clinically successful cases of bone device development, including biological glues, stem cell-seeded scaffolds, and gene-functionalized bone substitutes. We also discuss the ventures that these technologies went through, the hindrances they faced and the common grounds among them, which might have been key for their success. The ultimate objective of this perspective article is to highlight the important aspects of the clinical translation of an innovative idea in the field of bone grafting, with the aim of commercially and clinically informing new research approaches in the sector.

Bone Loss in Distal Radial Fractures Treated with A Composite Xenohybrid Bone Substitute: A Two Years Follow-Up Retrospective Study.

(1) Background: Recently, surgical treatment of distal radius fractures has increased exponentially. Many locking plates' fixation systems have been developed allowing a more stable reduction and early mobilization. Sometimes, open reduction and fixation of distal radius fractures may leave a residual bone loss requiring grafting. This retrospective study reports clinical and radiologic outcomes of distal radius fractures treated with xenohybrid bone grafting in order to assess (i) the safety of the investigated bone graft; (ii) its radiological integration and biomechanical performances, and (iii) clinical outcomes of the patients; (2) Methods: We performed a retrospective study on a cohort of 19 patients. Preoperative X-ray and CT scan were performed. The mean clinical and radiographical follow-up was two years. Safety of the xenohybrid bone graft was constantly evaluated. Clinical results were assessed through the DASH score and Mayo wrist score; (3) Results: No adverse reactions, infections, and local or general complication were related to the use of xenohybrid bone graft. The radiolucency of the xenografts suggested progressive osteointegration. No evidence of bone graft resorption was detected. All the patients reached consolidation with good to excellent clinical results; and (4) Conclusions: Clinical and radiological data demonstrated that xenohybrid bone grafting promotes new bone formation and healing in osteopenic areas caused by fracture reduction.

Permeation of Biopolymers Across the Cell Membrane: A Computational Comparative Study on Polylactic Acid and Polyhydroxyalkanoate.

Polymeric nanoparticles, which by virtue of their size (1-1000 nm) are able to penetrate even into cells, are attracting increasing interest in the emerging field of nanomedicine, as devices for, e.g., drugs or vaccines delivery. Because of the involved dimensional scale in the nanoparticle/cell membrane interactions, modeling approaches at molecular level are the natural choice in order to understand the impact of nanoparticle formulation on cellular uptake mechanisms. In this work, the passive permeation across cell membrane of oligomers made of two employed polymers in the biomedical field [poly-D,L-lactic acid (PDLA) and poly(3-hydroxydecanoate) (P3HD)] is investigated at fundamental atomic scale through molecular dynamics simulations. The free energy profile related to membrane crossing is computed adopting umbrella sampling. Passive permeation is also investigated using a coarse-grained model with MARTINI force field, adopting well-tempered metadynamics. Simulation results showed that P3HD permeation is favored with respect to PDLA by virtue of its higher hydrophobicity. The free energy profiles obtained at full atomistic and coarse-grained scale are in good agreement each for P3HD, while only a qualitative agreement was obtained for PDLA. Results suggest that a reparameterization of non-bonded interactions of the adopted MARTINI beads for the oligomer is needed in order to obtain a better agreement with more accurate simulations at atomic scale.

A Preliminary Study on the Mechanical Reliability and Regeneration Capability of Artificial Bone Grafts in Oncologic Cases, With and Without Osteosynthesis.

Several bone grafts are available for clinical use, each with their own peculiar biological and mechanical properties. A new bone graft was obtained by combining mineral structures from natural bovine bones with bioresorbable polymers and cellular nutrients. The study aims to evaluate the clinical, biological and structural properties of this bone graft and its reliability in orthopedic oncology. 23 adult patients (age range 18-85 years) were treated between October 2016 and December 2018; the oncologicdiagnoses were heterogeneous. After surgical curettage and bone grafting, a clinical-radiological follow up was conducted. Radiographs were used to evaluate graft integration according to the usual bone healing and oncologic follow up. Local complications (infection, local recurrence, wound dehiscence, fracture or early reabsorption) were evaluated. The mean followup was of 18.34 ± 4.83 months. No fracture or infection occurred. One case of patellar Giant Cell Tumor (GCT) and one of proximal tibia low-grade chondrosarcoma recurred after about one year. Two wound dehiscences occurred (one required a local flap). Follow-up X-rays showed good to excellent graft integration in most patients (20 out of 21). The investigated graft has a mechanical and structural function that can allow early weight-bearing and avoid a preventive bone fixation (only needed in four patients in this series). The graft blocks are different for shapes and dimensions, but they can be customized by the producer or sawcut by the surgeon in the operating theatre to fit the residual bone cavity. The complication rate was low, and a rapid integration was observed with no inflammatory reaction in the surrounding tissues. Further studies are mandatory to confirm these promising results.

Regenerative medicine for spinal cord injury: focus on stem cells and biomaterials.

INTRODUCTION: Spinal cord injury (SCI) is a dramatic medical pathology consequence of a trauma (primary injury). However, most of the post-traumatic degeneration of the tissue is caused by the so-called secondary injury, which is known to be a multifactorial process. This, indeed, includes a wide spectrum of events: blood-brain barrier dysfunction, local inflammation, neuronal death, demyelination and disconnection of nerve pathways. AREAS COVERED: Cell therapy represents a promising cure to target diseases and disorders at the cellular level, by restoring cell population or using cells as carriers of therapeutic cargo. In particular, regenerative medicine with stem cells represents the most appealing category to be used, thanks to their peculiar features. EXPERT OPINION: Many preclinical research studies demonstrated that cell treatment can improve animal sensory/motor functions and so demonstrated to be very promising for clinical trials. In particular, recent advances have led to the development of biomaterials aiming to promote in situ cell delivery. This review digs into this topic discussing the possibility of cell treatment to improve medical chances in SCI repair.

A Methodological Safe-by-Design Approach for the Development of Nanomedicines.

Safe-by-Design (SbD) concepts foresee the risk identification and reduction as well as uncertainties regarding human health and environmental safety in early stages of product development. The EU's NANoREG project and further on the H2020 ProSafe initiative, NanoReg2, and CALIBRATE projects have developed a general SbD approach for nanotechnologies (e.g., paints, textiles, etc.). Based on it, the GoNanoBioMat project elaborated a methodological SbD approach (GoNanoBioMat SbD approach) for nanomedicines with a focus on polymeric nanobiomaterials (NBMs) used for drug delivery. NBMs have various advantages such as the potential to increase drug efficacy and bioavailability. However, the nanoscale brings new challenges to product design, manufacturing, and handling. Nanomedicines are costly and require the combination of knowledge from several fields. In this paper, we present the GoNanoBioMat SbD approach, which allows identifying and addressing the relevant safety aspects to address when developing polymeric NBMs during design, characterization, assessment of human health and environmental risk, manufacturing and handling, and combines the nanoscale and medicine field under one approach. Furthermore, regulatory requirements are integrated into the innovation process.

Coating and Functionalization Strategies for Nanogels and Nanoparticles for Selective Drug Delivery.

Drug delivery is a fascinating research field with several development opportunities. Great attention is now focused on colloidal systems, nanoparticles, and nanogels and on the possibility of modifying them in order to obtain precise targeted drug delivery systems. The aim of this review is to give an overview of the main available surface functionalization and coating strategies that can be adopted in order to modify the selectivity of the nanoparticles in the delivery process and obtain a final system with great targeted drug delivery ability. We also highlight the most important fields of application of these kinds of delivery systems and we propose a comparison between the advantages and disadvantages of the described functionalization strategies.

Xenohybrid Bone Graft Containing Intrinsically Disordered Proteins Shows Enhanced In Vitro Bone Formation.

Bone defects are a significant health problem worldwide, as bone is the second-most transplanted tissue after blood. Although a myriad of bone grafts (BGs) have been used to treat bone repairs, none of them possesses all the desirable characteristics. An approach to improve BGs is to add bio-active components, however often difficult as BG production may disrupt the biological activities of such molecules. Here, we present a composite xenohybrid BG, SmartBonePep, with a type of biomolecule inspired by intrinsically disordered proteins (IDPs). These synthetic peptides (named P2 and P6) are physically entrapped into the polymer matrix of the composite BG. The effects of SmartBonePep on human osteoblasts were tested. Results showed that SmartBonePep enhanced proliferation and osteogenic effects. In order to verify the bioactivity of P2 and P6, these peptides were tested indirectly by being added to cell culture media too. Here, P2 or P6 exhibited promoting effects on osteogenic-related gene expressions. In this study, we showed highly effective osteoinductive synthetic peptides P2 or P6, which possess proline-rich and intrinsically disordered structural characters. This use of IDPs may provide promising bone enhancement biomolecules for clinical usage.

Xeno-Hybrid Bone Graft Releasing Biomimetic Proteins Promotes Osteogenic Differentiation of hMSCs.

Bone defect is a noteworthy health problem and is the second most transplanted tissue after blood. Numerous bone grafts are designed and applied in clinics. Limitations, however, from different aspects still exist, including limited supply, mechanical strength, and bioactivity. In this study, two biomimetic peptides (P2 and P6) are incorporated into a composite bioactive xeno hybrid bone graft named SmartBonePep®, with the aim to increase the bioactivity of the bone graft. The results, which include cytotoxicity, proliferation rate, confocal microscopy, gene expression, and protein qualification, successfully prove that the SmartBonePep® has multi-modal biological effects on human mesenchymal stem cells from bone marrow. The effective physical entrapment of P6 into a composite xeno-hybrid bone graft, withstanding manufacturing processes including exposure to strong organic solvents and ethylene oxide sterilization, increases the osteogenic potential of the stem cells as well as cell attachment and proliferation. P2 and P6 both show a strong biological potential and may be future candidates for enhancing the clinical performance of bone grafts.