Regenerative medicine of bone tissues

This team is composed of 37 people (20.8 full-time equivalent with 12 researchers with Research Supervisor Qualifications (HDR)). This team is headed by P. Weiss with V. Geoffroy as deputy head.

The REGOS team is a translational group focused on bone regeneration research with all the aspects related to this topic from physiopathology to 4R medical treatments (Replace, Repair, Regenerate, Reprogram). The REGOS team focuses on head bones from specialities of Odontology, Head and Neck as well as Maxillofacial surgery. Our research areas are bone apposition on mandibule and bone regeneration in periodontitis or peri implantitis, bone regeneration after irradiation for treatment of cancer, bone reconstruction in cleft and palate syndrome and long bone interruptive lesions. Our projects are divided into 4 themes from the basic science to the medical application: Molecular control of bone aging and bone regeneration (Theme 1), Hybrid biomaterials for bone scaffolds (Theme 2), Translational research in bone regeneration in ischemic bone (Theme 3) and Translational research in bone regeneration in periodontitis and peri-implantitis (Theme 4).  

Funding Bodies



Theme 1 - Molecular control of bone aging and regeneration

Leader: V. Geoffroy

The Epigen Team is composed of 2 senior scientists (V. Geoffroy DR Inserm, F. Jehan CR Inserm), 1 University associate Professor (A. Galvani, MCU), 1 technical staff (S. Tessier, Assistant Engineer).

This first theme deals with the fundamental processes controlling aging, degenerescence and the process of bone regeneration. This group aims to investigate novel mechanisms of osteoformation [microRNAs (Axe 1 ), epigenetic programs (Axe 2 ) and extracellular vesicles (Axe 3 )] and find target molecules that could contribute to reprogram stem cells.

Axe 1. Bone aging: regulation of bone formation by microRNAs – Application to bone regeneration - RegOmiR program

MicroRNAs play an important role in orchestrating age-related processes and in maintaining bone remodeling. This process involves the removal of old bone by osteoclasts (bone resorption) and its replacement by new bone formed by osteoblasts (bone formation). These microRNAs are small RNA (ribonucleic acid) whose main role is to inhibit gene expression. The goal of this project is to enhance in vivo bone regeneration using microRNAs and biomaterials. Our aim is to synchronize and better control the balance between scaffold-material resorption and new bone tissue formation, that are crucial aspects of tissue regeneration, and to produce new bone with excellent biomechanical properties.

Axe 2. Epigenetic control of gene expression during aging - iBone program 

Recent findings suggest that extrinsic factors influence skeletal metabolism during aging via their effects on osteoblasts (senescence, apoptosis and the capacity of pre-osteoblasts to fully differentiate). Extrinsic factors influence bone formation activity by osteoblasts in large part by inducing stable epigenomic programs, which direct the transcriptional program and phenotype of osteoblasts. We have started a targeted cell culture-based screening approach in order to identify putative osteoanabolic epigenome regulators (ANR-BMBF Bilateral iBone consortium). The ultimate aim of the iBone project is to identify age-related and osteoporosis-associated epigenomic modificators and their target genes, which can subsequently be used to uncover novel therapeutic targets.

Axe 3. Bone aging: regulation of bone formation by microvesicles - Application to bone regeneration - miRage Project

During ageing, bone neoformation by osteoblasts decreases drastically, resulting in progressive bone loss and an increasing risk of fracture. Abundant extracellular vesicles (EVs) are continually produced throughout life in response to many stimuli. EVs have been shown to carry signature proteins, functional nucleic acids including microRNAs (miRNAs), and other moieties that are characteristic of their cell of origin.

The miRage project aims to unravel a novel type of intercellular communication network that drives bone-formation and ultimately, bone mass. We hypothesize that stressed cells release EVs, and this vesiculation is a key event in the intercellular dialog in bone. We will demonstrate that 1/ bone EVs carry powerful signals, including miRNAs, to osteoblasts in order to control osteogenesis, 2/ bone EVs are altered during ageing, in quantity and quality, and 3/ these signals can be manipulated to rejuvenate osteoblasts, enhance their activity in vivo and stimulate bone regeneration.

Theme 1 collaborators:

O. Blanc-Brude (U970, PARCC, Paris), E. Hesse (University Medical Center Hamburg-Eppendorf, Germany), S Johnsen (University Medical Center Göttingen, Germany), M. Thomas-Chollier & D. Thieffry (ENS, Paris), J. Tost (Genopole, Evry).

Theme 2 - Hybrid biomaterials for bone scaffolds

Leader: P. Weiss

The HBBS Team is composed of 4 University/Hospital Professors (P. Weiss (PU-PH), H. Gauthier (MCU),  Zahi Badran (MCU-PH), Pierre Guihard (Associate professor), 1 senior scientist  (G. Daculsi DRE Inserm), 3 post-doc (A. Argun, B. Charbonnier, F. Fneich, ), 2 ITA (M. Lafont, L. Guyon).

This theme deals with the development of biomaterials for replacement, repair and regeneration of damaged bone tissues as well as the controlled release of cell reprograming molecules.

Axe 1. Calcium phosphate ceramics and combined injectable biomaterials - FLC Program and 2 industrial collaborations

In bone repair, osteoconductivity, osteogenicity and /or osteoinduction are prerequisites to favor bone ingrowth at the expense of the implant. The original approach of our laboratory was to focus on Calcium Phosphate (CaP) based biomaterials to support the challenge of “smart” scaffolds in bone regeneration (spine, orthopaedic, maxillofacial). Interactions between these mineral scaffold, biological fluids and cells are directly linked to resorbability of the scaffold, crystal size (submicronic, nanoscale, lattice defects at the molecular level), and 3D micro and macro architectures (porosity, 3D scaffold).

First, we will develop bioceramics with optimized specific ionic substitutions, synthesis protocols of micro/nanosized CaP crystals for low temperature sintering. These bioceramics will be designed with specific shape for stem cells and bone marrow combination (osteoinductive hollow granules for the niche concept). The bioceramics will be combined with soluble macromolecules associated with osteogenic factors (peptides) and/or cells.

Another aspect of our project is to develop biomaterials mimicking the natural bone extracellular matrix. We will use osteoconductive particles of CaP, associated with bone marrow MSCs, then combined with a viscous liquid phase, that can be injected prior to hydrogel cross-linking. We hypothesize that this combined biomaterial could protect the embedded cells inside the implanted area during bone healing. For that purpose, we are developping specific CaP micro/nanoneedles with high length/thickness ratio for percolation within a hydrogel, at low concentration.

First, we will develop bioceramics with optimized specific ionic substitutions, synthesis protocols of micro/nanosized CaP crystals for low temperature sintering. These bioceramics will be designed with specific shape for stem cells and bone marrow combination (osteoinductive hollow granules for the niche concept). The bioceramics will be combined with soluble macromolecules associated with osteogenic factors (peptides) and/or cells.


Axe 2. Responsive hydrogels - Gelihparbal Program and 3 Industrial collaborations

For bone regenerative medicine, hydrogels that mimic the extracellular matrix while being injectable, biocompatible, resorbable or degradable, and presenting tunable cross-linking kinetics are of interest, whether they are used as biomaterials (without cells) or as synthetic extra cellular matrix (with encapsulated cells). The “holly grail” of the REGOS team is to develop responsive hydrogels for bone and periodontal tissues regeneration that can adapt to the biological situation and stimulate the local environment. Our main focus will be to design hydrogels with i) tunable biodegradation properties, ii) enhanced oxygen diffusion properties and iii) ability to protect and release miRNA and extracellular vesicles as identified in Theme 1.

To control the hydrogel constructs degradability properties, we propose to incorporate various silated macromolecules into Si-HPMC hydrogel. Cationic chitosan and anionic hyaluronic acid known to be enzymatically biodegradable, will be investigated. We will assess the biodegradability of blends of macromolecules both in vitro and in vivo (subcutaneous implantation in mice), as well as their mechanical properties (gel point, stiffness).

For the POSTURE project (Euronanomed II), we will take advantage of the barrier effect of Si-HPMC. We will develop and characterize a photocrosslinked interpenetrating polymer network based on Si-HPMC and UV photosensitive methacrylated dextran that could be applied as a viscous solution and cured in situ with UV light. Their efficacy as a membrane to prevent the excessive proliferation of gingival tissue is currently assessed in a dog model of periodontal regeneration.

We also aim to develop hydrogels that could respond to local hypoxia. We propose to incorporate heme molecules from marine worms that can act as oxygen carriers, relasing oxygen when needed. We will first ensure that heme molecules do not interfere with the cross-lining process and we will validate the resulting hydrogel mechanical properties. We will assess the efficacy of the heme molecules to release oxygen upon cell culture and to rescue cells in hypoxia environment.

Theme 2 collaborators:

J. Le Bideau (Institut des matériaux de Nantes, S. Colliec (IFREMER, Nantes), JF Tassin and N. Taco (Institut des matériaux du Mans), F. Boury (Inserm UMR-S 1066, Angers), P. Delepine (EFS Bretagne U 1078), D. Barritault (OTR3), F. Zal (HEMARINA), N. Douard and D. Marchat, (Mines, ST-Etienne), C. Combes and C. Drouet, (CIRIMAT, Toulouse), N. Ignjatovic (Institute of technological science of Belgrade, Serbia), R Rohanizadeh (Faculty of Pharmacy, The University of Sydney).

Theme 3 - Translational research in bone regeneration in ischemic bone

Leaders: P. Corre/F. Espitalier

The Ischbone Team is composed of 6 University/Hospital Professors (P. Corre PHU, O. Malard  PU-PH, F. Espitalier MCU-PH, P. Blery MCU-PH, Y. Amouriq PU-PH, P Weiss PU-PH), 1 senior scientist (G. Daculsi DRE Inserm)

Axe 1. Tissue engineering for irradiated bone (F. Espitalier) - Ixbone Program

Cleft lip and palate is the most prevalent congenital craniofacial  malformation in humans. Cancer of the upper aero-digestive tract is one of the most frequent cancers. Head and neck cancer treatments have a drastic impact on patient life quality. Indeed, mandibular osteoradionecrosis (ORN) is a severe side effect of radiotherapy, which affects 5% of treated patients despite preventive actions. It leads to mandibular fractures, and deglutition and phonation disorders. The use of bone morphogenic proteins is not recommended because of side effects.

Axe 2. Tissue engineering for hypoplastic bone (P. Corre) - FUI Marbiotech, Fondation de l’avenir, les geules cassées

Large alveolar bone clefts cause social and aesthetical issues in children such as oronasal communications, speech defects, dental problems, and maxillary growth impairments. Bone substitutes or tissue engineering procedures, using biomaterials and mesenchymal stem cells (MSCs), have thus been used clinically but with limited success so far. In hypoplastic bone, the combination of Total Bone Marrow (TBM) associated with Biphasic Calcium Phosphate (BCP) has proven to be a simple and effective method compared to MSCs, which showed to be ineffective without growth factors. However, TBM harvesting is an invasive procedure and there is a great donor variability.

We propose to developp efficient hybrid constructs obtained by combining specific biomaterials developped in Theme 2, with biological signals, such as microRNA or extracellular vesicles identified in Theme 1. Using rat calvaria and maxillary large animal models, we will investigate the efficacy of such constructs notably for improving bone apposition and neo-vascularisation, and reducing bone inflammation.

Theme 3 collaborators:

N. Matthieu (IRSN, Fontenay-aux-Roses), JJ Lataillade (CTSA Percy U972), P. Delepine (EFS Bretagne U 1078), D. Barritault (OTR3), P. Matricardi (Sapienza University of Roma, Italy), J. Locs (Riga Technical University, Latvia), MH Fernandes (University of Porto, Portugal).

Theme 4 - Translational research in bone regeneration in periodontitis and peri-implantitis

Leader: P. Lesclous

This theme involves 5 University/Hospital Professor (P. Lesclous, A. Soueidan, Y. Amouriq, X. Struillou, A. Cloitre), 1 ONIRIS Professor (O. Gauthier), 1 University associate Professor (Z. Badran).

Axe 1 - Inflammation and resorption of bone in periodontitis

Periodontitis is a chronic inflammatory disease of bacterial origin that compromises the integrity of the tooth-supporting tissues. The end point of chronic periodontitis is destruction of alveolar bone leading to numerous teeth loss. The inflammatory mechanisms involved in the onset and progression of chronic periodontitis are not yet fully deciphered since no clear relevant inflammatory target of therapeutic interest have been clearly identified. New IL-1 family members that could be of huge interest in this perspective have been recently identified, especially IL-33, IL-36 and IL-38. IL-33 has recently been incriminated in the onset of chronic periodontitis  and our results strenghten these findings. Moreover, some immune cells i.e. the dendritic cells of the gingival tissue could play also a key role in bone loss associated to chronic periodontis through their own ability to trans-differentiate towards osteoclast upon inflammatory conditions. So, we hypothetize that these new IL-1 family members and the gingival dendritic cells could be major players in the progression of chronic periodontitis. Using in vivo (animal and human) and in vitro (cell cultures) approaches, we will further investigate the potential involvement of these cells and cytokines in the progression of chronic periodontitis. Ultimately, our goal is to identify therapeutic targets of interest in the treatment of chronic periodontitis.

Axe 2 - Regenerative medicine in periodonte - Posture program

Regenerative periodontal procedures aim to reverse this damage by using both a bone graft and a membrane to obtain a complete reconstruction of both hard tissue (alveolar bone and cementum) and soft tissue (periodontal ligament). To ensure that regenerative periodontal ligament cells and cementoblasts selectively repopulate the periodontal wound area, guided tissue regeneration relies on the use of a barrier. Thus, for periodontal guided tissue regeneration, hydrogels could be used as a membrane to isolate gum cells from the bone tissue, allowing bone ingrowth in the periodontal socket. In addition, it is well documented that cells may die inside a hydrogel construct due to local ischemia.

While polytetrafluoroethylene membranes require an additional procedure to be removed, resorbable bovine collagen membranes have a risk of disease transmission. In this context, we propose to develop an innovative periodontal regeneration device based on a self-setting silanized hydroxypropylmethycellulose hydrogel. We will develop a photocrosslinked interpenetrating polymer network (IPN) based on UV photosensitive methacrylated dextran that could be applied as a viscous solution and cured in situ with UV light (developed in Theme 2).

The cell occlusive effects of IPNs on human gingival fibroblasts will be studied and compared with those of expanded polytetrafluoroethylene membranes. Finally, we will validate the combination of the substituted CaP nanoparticles SiHPMC hydrogel as a bone graft and photocross-linked IPN as a membrane to prevent the excessive proliferation of gingival tissue in a dog model of periodontal regeneration.

Theme 4 collaborators:

F. Blanchard (UMR 1238 Phy-OS, Nantes), J. Caillon (EA 3826, Nantes), B. Ryffel (UMR 7355, Orléans), G. Palmer (University of Geneva, Switzerland), O. Huck (Inserm U 1109, Strasbourg), C. Blin (UMR 7370, LP2M, Nice).