Pierre Weiss

University of Nantes | UNIV Nantes · Faculté de Chirurgie Dentaire

In recent years, multicomponent hydrogels such as interpenetrating polymer networks (IPNs) have emerged as innovative biomaterials due to the synergistic combination of the properties of each network. We hypothesized that an innovative non-animal IPN hydrogel combining self-setting silanized hydroxypropyl methylcellulose (Si-HPMC) with photochemica...

The reconstruction of massive segmental mandibular bone defects (SMDs) remains challenging even today; the current gold standard in human clinics being vascularized bone transplantation (VBT). As alternative to this onerous approach, bone tissue engineering strategies have been widely investigated. However, they displayed limited clinical success,...

Injectable bone substitutes (IBS) represent compelling options for bone regenerative medicine as they can be used to optimally fill a complex bone defect through minimally invasive intervention. Since their discovery, calcium phosphate (CaP) based IBS have never stopped evolving to match the diverse clinical needs. The main challenge is to combine...

The development of instruments combining multiple characterization and imaging tools drove huge advances in material science, engineering, biology, and other related fields. Notably, the coupling of SEM with micro-Raman spectrometry (μRaman) provides the means for the correlation between structural and physicochemical properties at the surface, whi...

Additive manufacturing has attracted keen interest in the medical field in recent decades, especially for bone regeneration. Many additive manufacturing processes have been used to print medical devices such as implants, prostheses, and surgical guides, and for surgical planning in different medical fields, especially orthopedic, maxillofacial and...

Embedding mesenchymal stromal cells (MSCs) in biomaterial is a subject of increasing interest in the field of Regenerative Medicine. Speeding up the clinical use of MSCs is dependent on the use of non-syngeneic models in accordance with GMP (Good Manufacturing Practices) requirements and on costs. To this end, in this study we analyzed the in vivo...

The osteochondral (OC) unit plays a pivotal role in joint lubrication and in the transmission of constraints to bones during movement. The OC unit does not spontaneously heal; therefore, OC defects are considered to be one of the major risk factors for developing long‐term degenerative joint diseases such as osteoarthritis. Yet, there is currently...

Osteoradionecrosis (ORN) is one of the most feared side effects of radiotherapy following cancers of the upper aero-digestive tract and leading to severe functional defects in patients. Today, our lack of knowledge about the physiopathology restricts the development of new treatments. In this study, we refined the ORN rat model and quantitatively s...

Injectable hydrogels that polymerize directly in vivo hold significant promises in clinical settings to support the repair of damaged or failing tissues. Existing systems that allow cellular and tissue ingrowth after injection are limited because of deficient porosity and lack of oxygen and nutrient diffusion inside the hydrogels. Here is reported...

Biphasic calcium phosphate (BCP) granules are osteoconductive biomaterials used in clinics to favor bone reconstruction. Yet, poor cohesivity, injectability and mechanical properties restrain their use as bone fillers. In this study, we incorporated BCP granules into in situ forming silanized hyaluronic acid (Si-HA) and hydroxypropylmethylcellulose...

Autologous bone grafts (BGs) remain the reference grafting technique in various clinical contexts of bone grafting procedures despite their numerous peri-and post-operative limitations. The use of allogeneic bone is a viable option for overcoming these limitations, as it is reliable and it has been widely utilized in various forms for decades. Howe...

In skeletal surgical procedures, bone regeneration in irregular and hard-to-reach areas may present clinical challenges. In order to overcome the limitations of traditional autologous bone grafts and bone substitutes, an extrudable and easy-to-handle innovative partially demineralized allogenic bone graft in the form of a paste has been developed....

Tissue engineering is a multidisciplinary field that relies on the development of customized biomaterial to support cell growth, differentiation and matrix production. Toward that goal, we designed the grafting of silane groups onto the chitosan backbone (Si-chito) for the preparation of in situ setting hydrogels in association with silanized hydro...

In article number 2000981 by Pierre Weiss and co‐workers, an in situ forming, single‐component hyaluronic acid hydrogel is reported based on the pH‐triggered condensation of silanols into siloxanes. In vitro, cytocompatible hydrogels with tunable mechanical properties are obtained by tuning the crosslink density. In vivo, the hydrogel's degradabili...

In situ forming hydrogels that can be injected into tissues in a minimally‐invasive fashion are appealing as delivery vehicles for tissue engineering applications. Ideally, these hydrogels should have mechanical properties matching those of the host tissue, and a rate of degradation adapted for neo‐tissue formation. Here, the development of in situ...

Poly(ethylene glycol) (PEG) hydrogels have been extensively used as scaffolds for tissue engineering applications, owing to their biocompatibility, chemical versatility and tunable mechanical properties. However, their bio‐inert properties require them to be associated with additional functional moieties to interact with cells. To circumvent this n...

Repairing mandibular bone defects after radiotherapy of the upper aerodigestive tract is clinically challenging. Although bone tissue engineering has recently generated a number of innovative treatment approaches for osteoradionecrosis, these modalities must be evaluated preclinically in a relevant, reproducible, animal model. The objective of the...

The survival and function of thick tissue engineered implanted constructs depends on pre-existing, embedded, functional, vascular-like structures that are able to integrate with the host vasculature. Bioprinting was employed to build perfusable vascular-like networks within thick constructs. However, the improvement of oxygen transportation facilit...

Background & Aim Healthy tissues surrounding pelvic tumours may be impaired during radiotherapy (RT) and could lead to chronic gastrointestinal complications with substantial mortality. Injection of Adipose-derived Mesenchymal Stromal Cells (Ad-MSC) represents a promising therapeutic strategy. However, many stem cell clinical trials do not confer e...

TISSUE ENGINEERING IN ENDODONTICS Tissue engineering is an interdisciplinary science that involves the use of biological sciences and engineering to develop tissues that restore, maintain, or enhance tissue function of a tissue or an organ. Initially developed in medicine in the 1980s for skin reconstructions, tissue engineering has extended to odo...

Articular cartilage (AC) may be affected by many injuries including traumatic lesions that predispose to osteoarthritis. Currently there is no efficient cure for cartilage lesions. In that respect, new strategies for regenerating AC are contemplated with interest. In this context, we aim to develop and characterize an injectable, self-hardening, me...

Objective: To determine the ability of three implants to enhance the healing of osteochondral defects: (1) a biphasic construct composed of calcium phosphate (CaP) and chitosan/cellulosic polymer, (2) a titanium-polyurethane implant, and (3) an osteochondral autograft. Study design: Experimental study. Animals: Ten adult female sheep. Methods...

The aim of the systematic review was to analyze the use of mesenchymal stem cells (MSC) and biomaterial for periodontal regeneration from preclinical animal models and human. Electronic databases were searched and additional hand-search in leading journals was performed. The research strategy was achieved according to the Preferred Reporting Items...

Finding alternative strategies for the regeneration of craniofacial bone defects (CSD), such as combining a synthetic ephemeral calcium phosphate (CaP) implant and/or active substances and cells, would contribute to solving this reconstructive roadblock. However, CaP’s architectural features (i.e., architecture and composition) still need to be tai...

Background: The reconstruction of segmental mandibular defects remains a challenge for the reconstructive surgeon, from both a functional and an esthetic point of view. Methods: This clinical review examines the different techniques currently in use for mandibular reconstruction as related to a range of etiologies, including the different bone d...

Hydroxyapatite (HA) has received much interest for being used as bone substitutes because of its similarity with bioapatites. In form of nanowires or nanotubes, HA would offer more advantages such as better biological and mechanical properties than conventional particles (spherical). To date, no study had allowed the isolated nanowires production w...

Clinical expression of gastrointestinal radiation toxicity on non-cancerous tissue could be very life threatening and clinicians must deal increasingly with the management of late side effects of radiotherapy. Cell therapy, in particular mesenchymal stromal cell (MSC) therapy, has shown promising results in numerous preclinical animal studies and t...

Background: In craniofacial reconstruction, the gold standard procedure for bone regeneration is the autologous bone graft (BG). However, this procedure requiring bone harvesting is a source of morbidity. Bone substitutes, such as biphasic calcium phosphate (BCP), represent an interesting alternative but are not sufficient for bone healing in hypo...

Introduction: Following any oral surgery procedure, postoperative pain is an inevitable outcome and can be described as moderate to severe. The pain management is essential for the comfort and the well-being of the patients. Topical delivery and more specifically transmucosal delivery systems seem to be of great value for the development of new pai...

Objective Periodontitis is an inflammatory disease that destroys the tooth-supporting attachment apparatus. Guided tissue regeneration (GTR) is a technique based on a barrier membrane designed to prevent wound space colonization by gingival cells. This study examined a new formulation composed of two polymers that could be photochemically cross-lin...

During skeletal mineralization, the sodium‐phosphate co‐transporter PiT1Slc20a1 is assumed to meet the phosphate requirements of bone‐forming cells, although evidence is missing. Here, we used a conditional gene deletion approach to determine the role of PiT1 in growth plate chondrocytes. We show that PiT1 ablation shortly after birth generates a r...

Silanized hydroxypropyl methylcellulose based hydrogels were developed for cartilage and intervertebral disc tissue engineering. Herein, study of dynamics of confined water showed two different populations, identified as hydration and bulk-like water. The diffusion coefficient showed that bulk-like water diffuses over distances ∼10 μm without being...

The aim of the study was to evaluate bone regeneration using a canine model with surgically created periodontal defects filled for 12 weeks using a stratified biomaterial consisting in a biphasic calcium phosphate (BCP) covered with a crosslinking hydrogel acting as polymer membrane of silated hydroxypropyl methylcellulose (Si-HPMC) as the tested n...

Human adipose-derived stromal cells (hASCs) are widely known for their immunomodulatory and anti-inflammatory properties. This study proposes a method to protect cells during and after their injection by encapsulation in a hydrogel using a droplet millifluidics technique. A biocompatible, self-hardening biomaterial composed of silanized-hydroxyprop...

Laponite XLS™, which is a synthetic clay of nanometric dimensions containing a peptizing agent, has been associated with silanized hydroxypropylmethylcellulose (Si-HPMC) to form, after crosslinking, a novel composite hydrogel. Different protocols of sample preparation were used, leading to different morphologies. A key result was that the storage m...

[This corrects the article DOI: 10.1371/journal.pone.0178060.].

Hydrogels are attractive biomaterials for replicating cellular microenvironments, but attention needs to be given to hydrogels diffusion properties. A large body of literature shows the promise of hydrogels as 3D culture models, cell expansion systems, cell delivery vehicles and tissue constructs. Surprisingly, literature seems to have overlooked t...

Discogenic low back pain is considered a major health concern and no etiological treatments are today available to tackle this disease. To clinically address this issue at early stages, there is a rising interest in the stimulation of local cells by in situ injection of growth factors targeting intervertebral disc (IVD) degenerative process. Despit...

Significance: Articular Cartilage is a tissue that fails to heal spontaneously. To address this clinically relevant issue, biomaterial-assisted cell therapy is considered promising but they are often lacking in mechanical properties. Our objective was to develop a composite hydrogel using a small amount of nano reinforcement (laponite) capable of...

While therapeutically interesting, the injection of MSCs suffers major limitations including cell death upon injection and a massive leakage outside the injection site. We proposed to entrap MSCs within spherical particles derived from alginate, as a control, or from silanized hydroxypropyl methylcellulose (Si-HPMC). We developed water in an oil di...

Alteromonas infernus bacterium isolated from deep-sea hydrothermal vents can produce by fermentation a high molecular weight exopolysaccharide (EPS) called GY785. This EPS described as a new source of glycosaminoglycan-like molecule presents a great potential for pharmaceutical and biotechnological applications. However, this unusual EPS is secrete...

Tissue engineering strategies have been developed to optimize osseointegration in dental implant surgery. One of the major problems is the non-homogeneous spatial cell distribution in the scaffold, as well as subsequent matrix production. Insufficient nutrient and oxygen supplies inside the scaffold are factors in this phenomenon. To mediate this g...

Repairing or replacing damaged human tissues has been the ambitious goal of regenerative medicine for over 25 years. One promising approach is the use of hydrated three-dimensional scaffolds, known as hydrogels, which have had good results repairing tissues in pre-clinical trials. Benefiting from breakthrough advances in the field of biology, and m...

Combined therapy is a global strategy developed to prevent drug resistance in cancer and infectious diseases. In this field, there is a need of multifunctional drug delivery systems able to co-encapsulate small drug molecules, peptides, proteins, associated to targeting functions, nanoparticles. Silylated hydrogels are alkoxysilane hybrid polymers...

Mandibular osteoradionecrosis is a severe side effect of radiotherapy after the treatment of squamous cell carcinomas of the upper aerodigestive tract. As an alternative to its treatment by micro-anastomosed free-flaps, preclinical tissular engineering studies have been developed. Total bone marrow (TBM) associated with biphasic calcium phosphate (...

Quantitative SEM study: Datas after semi-automatic image analyzer procedure. (XLSX)

Drug delivery systems are proposed for the in situ controlled delivery of therapeutic molecules in the scope of tissue engineering. We propose herein silica nanofibers as carrier for the loading and release of bioactive proteins. The influence of pH, time and concentration on the amount of adsorbed proteins was studied. The interactions allowing lo...

Healthy tissues surrounding abdomino-pelvic tumours can be impaired by radiotherapy, leading to chronic gastrointestinal complications with substantial mortality. Adipose-derived Mesenchymal Stromal Cells (Ad-MSCs) represent a promising strategy to reduce intestinal lesions. However, systemic administration of Ad-MSCs results in low cell engraftmen...

Bone substitutes, used to fill a defect after a surgery or a trauma, provide a mechanical support and might induce bone healing. They constitute an alternative to autogenous bone grafts, the 'gold standard' which remains the reference despite its risk of postoperative complications. The clinician choice of a bone substitute is based on the required...

Xeno-cell therapy from neonate or adult pig pancreatic islets is one of the most promising alternatives to allograft in type-1 diabetes for addressing organ-shortage. However, in human, natural and elicited antibodies specific for pig xenoantigens, α(1,3)-galactose (GAL) and N-glycolylneuraminic acid (Neu5Gc), are likely to significantly contribute...

Background: Autologous fat grafting is a widely used technique that gives natural results when treating soft tissue deficiencies. However, there is no consensus on which is the best procedure to use, leading to unpredictable results because of fat graft resorption. Objectives: This study compared four commercial lipotransfer devices by analyzing...

For hybrid materials, the relationship between the macroscopic properties and the molecular structures and dynamics at the microscopic between the organic and inorganic components level is crucial. The characterization of these components as well as their reactivity have to be emphasized in order to design and synthesize improved hybrids. We report...

Introduction: The dentin extracellular matrix is a reservoir of bioactive molecules sequestered into dentin during dental initial development. They can be released under pathological conditions but also by controlled demineralization with bioactive materials. The purpose of this study was to investigate the ability of a biomedical hydrogel to extr...

Interpenetrated gels of biocompatible polysaccharides alginate and silanized hydroxypropyl methyl cellulose (Si-HPMC) have been studied in order to assess their potential as scaffolds for the regeneration of human tissues. Si-HPMC networks were formed by reduction of the pH to neutral and alginate networks were formed by progressive in situ release...