Osteogenic Potential of a Biomaterial Enriched with Osteostatin and Mesenchymal Stem Cells in Osteoporotic Rabbits.

Mesoporous bioactive glasses (MBGs) of the SiO2-CaO-P2O5 system are biocompatible materials with a quick and effective in vitro and in vivo bioactive response. MBGs can be enhanced by including therapeutically active ions in their composition, by hosting osteogenic molecules within their mesopores, or by decorating their surfaces with mesenchymal stem cells (MSCs). In previous studies, our group showed that MBGs, ZnO-enriched and loaded with the osteogenic peptide osteostatin (OST), and MSCs exhibited osteogenic features under in vitro conditions. The aim of the present study was to evaluate bone repair capability after large bone defect treatment in distal femur osteoporotic rabbits using MBGs (76%SiO2-15%CaO-5%P2O5-4%ZnO (mol-%)) before and after loading with OST and MSCs from a donor rabbit. MSCs presence and/or OST in scaffolds significantly improved bone repair capacity at 6 and 12 weeks, as confirmed by variations observed in trabecular and cortical bone parameters obtained by micro-CT as well as histological analysis results. A greater effect was observed when OST and MSCs were combined. These findings may indicate the great potential for treating critical bone defects by combining MBGs with MSCs and osteogenic peptides such as OST, with good prospects for translation to clinical practice.

Preliminary results of customized bone graft made by robocasting hydroxyapatite and tricalcium phosphates for oral surgery.

OBJECTIVE: The objective of this study was to assess the mechanical characteristics and the clinical usefulness of beta-tricalcium phosphate (ß-TCP) and hydroxyapatite (HA) bioblocks grafted in edentulous jaws of 12 patients. METHODS: The scaffolds were produced by robocasting ceramic inks containing 80%/20% ß-TCP and HA, respectively, with an overall porosity of 60%, with a macropore size between 300 and 500 µm. The mechanical performance of cylindrical vs conical specimens was compared using a universal testing machine. The clinical study was performed on 12 edentulous patients who received 4 cylindrical bone bioblocks. After 10 to 16 weeks of osseointegration, the bioblocks were explanted with trephine for histologic analysis by Goldner and Von Kossa staining. RESULTS: Conical shapes were significantly stronger (96.4 ± 8.7 MPa) than cylindrical shapes (87.8 ± 12.2 MPa). The overall degree of porosity ranged from 53.4% to 58.1% in the coronal region to 62.5% to 66.9% at the apex. After the maturation period, 41 valid bioblocks (85.4%) were obtained for histologic study. Bone showing some cellularity was found in 68.4% of the samples, indicating biologically active bone, and adequate calcification was found in 31.7% of the samples. In terms of biomaterial degradation, 73.2% of the samples were completely resorbed or showed significant resorption. CONCLUSIONS: The 80%/20% ß-TCP and HA grafts customized by robocasting appear adequate for regenerating self-contained defects.

Histologic Outcomes of the Use of Different Biomaterials for Socket Regeneration in Fresh Extraction Sockets: A Split-Mouth Randomized Clinical Trial.

PURPOSE: To analyze the quality of bone regeneration in fresh sockets using four different materials at different time points. MATERIALS AND METHODS: A split-mouth randomized clinical trial was designed to evaluate the histologic and histomorphometric characteristics of 82 fresh sockets from 30 patients. One socket per patient healed spontaneously (control), and at least one fresh socket was grafted with a material chosen randomly from a sealed envelope: plateletrich growth factor (PRGF; n = 20 sites), PRGF + autologous bone (n = 9 sockets), autologous bone (n = 10 sites), or PRGF + demineralized freeze-dried bone allograft (DFDBA; n = 13). Biopsy specimens were taken at different time points divided into three assessment groups: short duration (2 to 4 months), intermediate duration (5 to 6 months), and long duration (7 to 12 months). The histologic findings were assessed to quantify the trabeculae pattern, the degree of mineralization, and the quality of bone regeneration. RESULTS: A total of 26 patients with 73 sockets completed the study. Mineralization after a short duration was found to be significantly higher among sockets treated only with autologous bone (47.3% ± 3.6%) or with PRGF+autologous bone (45.1% ± 13.6%). During the intermediate time point, this difference was not observed; also, the control sites were found to have the highest amount of mineralization (37.7% ± 14.9%). After a long duration of wound healing, the PRGF+DFDBA group had the greatest percentage of mineralized tissue (54.7% ± 28.7%), which was significantly higher than the sites treated only with PRGF (30.0% ± 13.2%). CONCLUSION: From a histologic point of view, the use of autologous graft with or without PRGF seems to be the best strategy for socket regeneration within a short period of time (2 to 4 months). However, the application of PRGF alone inside fresh sockets may interfere with normal bone healing compared with control sites healed spontaneously.

Effect Morphology and Surface Treatment of the Abutments of Dental Implants on the Dimension and Health of Peri-Implant Biological Space.

STATEMENT OF THE PROBLEM: The gingival configuration around implant abutments is of paramount importance for preserving the underlying marginal bone, and hence for the long-term success of dental implants. OBJECTIVE: The objective was to study, clinically and histologically, the effects of the change in the morphology of abutments connected to the endosseous implant, and of their surface treatment. In particular, the objective was to ascertain the effect of changing the shape of the transepithelial pillar and the treatment of its surface on the dimensions, quality and health of the components of the peri-implant biological space, such as the dimensions of the epithelial and connective tissues of the biological space, the concentration of inflammatory cells and the density of collagen fibers. METHODS: A clinical trial of 10 patients with a totally edentulous maxilla, who had four implants (IPX4010_GALIMPLANT®, Sarria, Spain) inserted in the area of the first and second molars on both sides with computer-guided implant surgery, was conducted with the final purpose of assessing the quality of the peri-implant soft tissue attachment around the transepithelial abutments which were employed (aesthetic machined (RM), aesthetic anodized (RA), slim machined (SM) and slim anodized (SA)). At 8 weeks and following the collection of the samples (removal of the implant-abutment assembly with its surrounding hard and soft tissue) and their processing for subsequent histological and histomorphometric analysis in order to study the dimensions, quality and health of the peri-implant soft tissue area, the variables previously mentioned were determined according to the aims of the study. By using appropriate diameter trephine in order to obtain a useful fringe of soft tissue around the transepithelial pillars, ANOVA and chi-square tests were performed. RESULTS: The SPSS statistical analysis ANOVA results revealed that the machined slim abutments have a better performance considering the variables analyzed with epithelial and connective attachment heights of 1.52 mm and 2.3 mm, respectively, and that connective density (density of collagen fibers) was high at 85.7% of the sample size affected by the design for the slim abutments and 92.9% of the high-density sample size affected by the surface treatment for the machined surface. CONCLUSIONS: All variables studied, despite the small sample size, showed the superiority of the slim machined abutment among the four groups.

Anterior cruciate ligament innervation in primary knee osteoarthritis.

OBJECTIVE: To relate the Anterior Cruciate Ligament (ACL) innervation and histologic degeneration status to the knee osteoarthritis radiologic and functional status. DESIGN: Prospective observational study including 30 consecutive patients affected by primary knee osteoarthritis undergoing Total Knee Arthroplasty (TKA). All patients suffering secondary knee osteoarthritis, an antecedent of an infectious process, malignant process, autoimmune disorder, or previous knee surgery were excluded. We recorded biodemographic, clinical, and radiologic variables of all participants previous to the TKA procedure. ACL tissue was harvested during TKA standard procedure and the obtained sample was fixed in 4% formalin and paraffin-embedded. ACL cross-sections were stained by haematoxylin-eosin and Gallego staining for elastic and collagen fibers, and Sevier-Munger silver staining for nervous tissue. RESULTS: ACL samples histologic degeneration classification reported 15.4% normal, 23.1% slight, 26.9% mild, 11.5% moderate and 23.1% marked. We noted 46.2% large nervous fascicles, 15.4% medium fascicles, 3.8% small fascicles, and no nerve fibers were found in 34.6% ACL samples. No significant correlation was found between the histologic degeneration and the nervous fiber quantification (p>0.05, in all cases). We noted a significant histologic degeneration inverse correlation with the VAS scale (p=0.016), and nervous fiber quantification correlation with Lequesne maximum distance walked punctuation (p=0.043). We also noted greater nervous fiber quantification with minor radiological knee osteoarthritis (Kellgren-Lawrence grade II). CONCLUSIONS: ACL degeneration and innervation deficit may play a role in primary knee osteoarthritis onset, but the lack of a defining relationship among the different parameters assessed justifies further research in greater populations.

Modulation of Inflammatory Mediators by Polymeric Nanoparticles Loaded with Anti-Inflammatory Drugs.

The first-line treatment of osteoarthritis is based on anti-inflammatory drugs, the most currently used being nonsteroidal anti-inflammatory drugs, selective cyclooxygenase 2 (COX-2) inhibitors and corticoids. Most of them present cytotoxicity and low bioavailability in physiological conditions, making necessary the administration of high drug concentrations causing several side effects. The goal of this work was to encapsulate three hydrophobic anti-inflammatory drugs of different natures (celecoxib, tenoxicam and dexamethasone) into core-shell terpolymer nanoparticles with potential applications in osteoarthritis. Nanoparticles presented hydrodynamic diameters between 110 and 130 nm and almost neutral surface charges (between -1 and -5 mV). Encapsulation efficiencies were highly dependent on the loaded drug and its water solubility, having higher values for celecoxib (39-72%) followed by tenoxicam (20-24%) and dexamethasone (14-26%). Nanoencapsulation reduced celecoxib and dexamethasone cytotoxicity in human articular chondrocytes and murine RAW264.7 macrophages. Moreover, the three loaded systems did not show cytotoxic effects in a wide range of concentrations. Celecoxib and dexamethasone-loaded nanoparticles reduced the release of different inflammatory mediators (NO, TNF-α, IL-1ß, IL-6, PGE2 and IL-10) by lipopolysaccharide (LPS)-stimulated RAW264.7. Tenoxicam-loaded nanoparticles reduced NO and PGE2 production, although an overexpression of IL-1ß, IL-6 and IL-10 was observed. Finally, all nanoparticles proved to be biocompatible in a subcutaneous injection model in rats. These findings suggest that these loaded nanoparticles could be suitable candidates for the treatment of inflammatory processes associated with osteoarthritis due to their demonstrated in vitro activity as regulators of inflammatory mediator production.

Amphiphilic polymeric nanoparticles encapsulating curcumin: Antioxidant, anti-inflammatory and biocompatibility studies.

Oxidative stress and inflammation are two related processes common to many diseases. Curcumin is a natural compound with both antioxidant and anti-inflammatory properties, among others, that is recently being used as a natural occurring product alternative to traditional drugs. However, it has a hydrophobic nature that compromises its solubility in physiological fluids and its circulation time and also presents cytotoxicity problems in its free form, limiting the range of concentrations to be used. In order to overcome these drawbacks and taking advantage of the benefits of nanotechnology, the aim of this work is the development of curcumin loaded polymeric nanoparticles that can provide a controlled release of the drug and enlarge their application in the treatment of inflammatory and oxidative stress related diseases. Specifically, the vehicle is a bioactive terpolymer based on a α-tocopheryl methacrylate, 1-vinyl-2-pyrrolidone and N-vinylcaprolactam. Nanoparticles were obtained by nanoprecipitation and characterized in terms of size, morphology, stability, encapsulation efficiency and drug release. In vitro cellular assays were performed in human articular chondrocyte and RAW 264.7 cultures to assess cytotoxicity, cellular uptake, antioxidant and anti-inflammatory properties. The radical scavenging activity of the systems was confirmed by the DPPH test and the quantification of cellular reactive oxygen species. The anti-inflammatory potential of these systems was demonstrated by the reduction of different pro-inflammatory factors such as IL-8, MCP and MIP in chondrocytes; and nitric oxide, IL-6, TNF-α and MCP-1, among others, in RAW 264.7. Finally, the in vivo biocompatibility was confirmed in a rat model by subcutaneously injecting the nanoparticle dispersions. The reduction of curcumin toxicity and the antioxidant, anti-inflammatory and biocompatibility properties open the door to deeper in vitro and in vivo research on these curcumin loaded polymeric nanoparticles to treat inflammation and oxidative stress based diseases.

Biomimetic Gradient Scaffolds Containing Hyaluronic Acid and Sr/Zn Folates for Osteochondral Tissue Engineering.

Regenerative therapies based on tissue engineering are becoming the most promising alternative for the treatment of osteoarthritis and rheumatoid arthritis. However, regeneration of full-thickness articular osteochondral defects that reproduces the complexity of native cartilage and osteochondral interface still remains challenging. Hence, in this work, we present the fabrication, physic-chemical characterization, and in vitro and in vivo evaluation of biomimetic hierarchical scaffolds that mimic both the spatial organization and composition of cartilage and the osteochondral interface. The scaffold is composed of a composite porous support obtained by cryopolymerization of poly(ethylene glycol) dimethacrylate (PEGDMA) in the presence of biodegradable poly(D,L-lactide-co-glycolide) (PLGA), bioactive tricalcium phosphate ß-TCP and the bone promoting strontium folate (SrFO), with a gradient biomimetic photo-polymerized methacrylated hyaluronic acid (HAMA) based hydrogel containing the bioactive zinc folic acid derivative (ZnFO). Microscopical analysis of hierarchical scaffolds showed an open interconnected porous open microstructure and the in vitro behaviour results indicated high swelling capacity with a sustained degradation rate. In vitro release studies during 3 weeks indicated the sustained leaching of bioactive compounds, i.e., Sr2+, Zn2+ and folic acid, within a biologically active range without negative effects on human osteoblast cells (hOBs) and human articular cartilage cells (hACs) cultures. In vitro co-cultures of hOBs and hACs revealed guided cell colonization and proliferation according to the matrix microstructure and composition. In vivo rabbit-condyle experiments in a critical-sized defect model showed the ability of the biomimetic scaffold to promote the regeneration of cartilage-like tissue over the scaffold and neoformation of osteochondral tissue.

Nanostructured Zn-Substituted Monetite Based Material Induces Higher Bone Regeneration Than Anorganic Bovine Bone and ß-Tricalcium Phosphate in Vertical Augmentation Model in Rabbit Calvaria.

The capacity of a nanostructured multicomponent material composed of Zn-substituted monetite, amorphous calcium phosphate, hydroxyapatite and silica gel (MSi) to promote vertical bone augmentation was compared with anorganic bovine bone (ABB) and synthetic ß-tricalcium phosphate (ß-TCP). The relation between biological behavior and physicochemical properties of the materials was also studied. The in vivo study was conducted in a vertical bone augmentation model in rabbit calvaria for 10 weeks. Significant differences in the biological behavior of the materials were observed. MSi showed significantly higher bone regeneration (39%) than ABB and ß-TCP (24%). The filled cylinder volume was similar in MSi (92%) and ABB (91%) and significantly lower in ß-TCP (81%) implants. In addition, ß-TCP showed the highest amount of non-osteointegrated particles (17%). MSi was superior to the control materials because it maintains the volume of the defect almost full, with the highest bone formation, the lowest number of remaining particles, which are almost fully osteointegrated and having the lowest amount of connective tissue. Besides, the bone formed was mature, with broad trabeculae, high vascularization and osteogenic activity. MSi resorbs gradually over time with an evident increment of the porosity and simultaneous colonization for vascularized new bone. In addition, the osteoinductive behavior of MSi material was evidenced.

The Impact of Compaction Force on Graft Consolidation in a Guided Bone Regeneration Model.

PURPOSE: Compaction of particulated grafts is done manually; thus, the effect of compression force on bone regeneration remains unclear. The aim of this study was to evaluate the impact of two different compression forces on the consolidation of particulated bovine hydroxyapatite. MATERIALS AND METHODS: Two titanium cylinders were fixed on the calvarium of eight New Zealand rabbits. Both defects were filled with particulated bovine hydroxyapatite subjected to a compression force of 0.7 kg/cm2 or 1.6 kg/cm2 before being covered with a resorbable collagen membrane. A handheld device that uses a spring to control the compression force applied by the plugger was used. At 6 weeks, histomorphometry of the area immediately adjacent to the calvaria bone and to the collagen membrane was performed. RESULTS: It was shown that next to the calvaria, the bone volume per tissue volume (BV/TV) was 29.0% ± 8.8% and 27.6% ± 8.2% at low and high compression force, respectively; the bone-to-biomaterial contact (BBC) was 58.2% ± 25.0% and 69.3% ± 22.9%, respectively (P > .05). In the corresponding area next to the collagen membrane, BV/TV was 4.9% ± 5.1% and 5.7% ± 4.7%, and the BBC was 18.3% ± 20.8% and 20.1% ± 15.9%, respectively (P > .05). In addition, the number and area of blood vessels were not significantly affected by compression force. CONCLUSION: Both compression forces applied resulted in similar consolidation of bovine hydroxyapatite expressed by new bone formation and vascularization based on a rabbit calvaria augmentation model.

Novel Osteoinductive and Osteogenic Scaffolds of Monetite, Amorphous Calcium Phosphate, Hydroxyapatite, and Silica Gel: Influence of the Hydroxyapatite/Monetite Ratio on Their In Vivo Behavior and on Their Physical and Chemical Properties.

In this work, a new family of multiphasic materials composed of the same amount of silica gel and variable amount of three calcium phosphates with very different solubilities, monetite > amorphous calcium phosphate > hydroxyapatite (HAp), was studied. Silicon was added to calcium phosphate to increase bioactivity and osteinductivity. The influence of the HAp/monetite ratio on the material resorption and bone regeneration was investigated in critical bone defects in sheep and was related to their chemical and physical properties. It was concluded that a minimum rate of HAp/monetite is necessary to achieve an appropriate compromise between material resorption and bone regeneration. Above this minimum rate, bone regeneration and material resorbtion did not change significantly. Physical properties such as particle size, specific surface area, porosity, and granulate cohesion played a more critical role on material resorption than the solubility of their components. A huge difference between in vitro solubility and in vivo resorption was observed. It was related to the fastest cellular-mediated resorption of monetite compared to the other components. Computerized axial tomography, histology, histomorphometric, and multiple fluorochrome labeling studies showed a very advanced bone regeneration of the defects when materials with the highest HAp/monetite rate were implanted. It was also demonstrated that all materials induce bone formation and vascularization.

Bioadhesive functional hydrogels: Controlled release of catechol species with antioxidant and antiinflammatory behavior.

Chronic wounds are particularly difficult to heal and constitute an important global health care problem. Some key factors that make chronic wounds challenging to heal are attributed to the incessant release of free radicals, which activate the inflammatory system and impair the repair of the wound. Intrinsic characteristics of hydrogels are beneficial for wound healing, but the effective control of free radical levels in the wound and subsequent inflammation is still a challenge. Catechol, the key molecule responsible for the mechanism of adhesion of mussels, has been proven to be an excellent radical scavenger and anti-inflammatory agent. Our approach in this work lies in the preparation of a hybrid system combining the beneficial properties of hydrogels and catechol for its application as a bioactive wound dressing to assist in the treatment of chronic wounds. The hydrogel backbone is obtained through a self-covalent crosslinking between chitosan (Ch) and oxidized hyaluronic acid (HAox) in the presence of a synthetic catechol terpolymer, which is subsequently coordinated to Fe to obtain an interpenetrated polymer network (IPN). The structural analysis, catechol release profiles, in vitro biological behavior and in vivo performance of the IPN are analyzed and compared with the semi-IPN (without Fe) and the Ch/HAox crosslinked hydrogels as controls. Catechol-containing hydrogels present high tissue adhesion strength under wet conditions, support growth, migration and proliferation of hBMSCs, protect cells against oxidative stress damage induce by ROS, and promote down-regulation of the pro-inflammatory cytokine IL-1ß. Furthermore, in vivo experiments reveal their biocompatibility and stability, and histological studies indicate normal inflammatory responses and faster vascularization, highlighting the performance of the IPN system. The novel IPN design also allows for the in situ controlled and sustained delivery of catechol. Therefore, the developed IPN is a suitable ECM-mimic platform with high cell affinity and bioactive functionalities that, together with the controlled catechol release, will enhance the tissue regeneration process and has a great potential for its application as wound dressing.

Human Bone Marrow Mesenchymal Stromal Cells Promote Bone Regeneration in a Xenogeneic Rabbit Model: A Preclinical Study.

Significant research efforts have been undertaken during the last decades to treat musculoskeletal disorders and improve patient's mobility and quality of life. The goal is the return of function as quickly and completely as possible. Cellular therapy has been increasingly employed in this setting. The design of this study was focused on cell-based alternatives. The present study aimed at investigating the bone regeneration capacity of xenogeneic human bone marrow-derived mesenchymal stromal cell (hMSC) implantation with tricalcium phosphate (TCP) granules in an immunocompetent rabbit model of critical-size bone defects at the femoral condyles. Two experimental groups, TCP and hMSC + TCP, were compared. Combination of TCP and hMSC did not affect cell viability or osteogenic differentiation. We also observed significantly higher bone regeneration in vivo in the hMSC + TCP group, which also displayed better TCP osteointegration. Also, evidence of hMSC contribution to a better TCP osteointegration was noticed. Finally, no inflammatory reaction was detected, besides the xenotransplantation of human cells into an immunocompetent recipient. In summary, hMSC combined with TCP granules is a potential combination for bone regeneration purposes that provides better preclinical results compared to TCP alone.

In Situ Cross-Linkable Polymer Systems and Composites for Osteochondral Regeneration.

Injectable hydrogels have demonstrated being a promising strategy for cartilage and bone tissue engineering applications, owing to their minimal invasive injection procedure, easy incorporation of cells and bioactive molecules, improved contact with the surrounding tissues and ability to match defects with complex irregular shapes, characteristics of osteoarthritic pathology. These unique properties make them highly suitable bioscaffolds for treating defects which are otherwise not easily accessible without and invasive surgical procedure. In this book chapter it has been summarized the novel appropriate injectable hydrogels for cartilage and bone tissue engineering applications of the last few years, including the most commonly used materials for the preparation, both natural and synthetic, and their fabrication techniques. The design of a suitable injectable hydrogel with an adequate gelation time that gathers perfect bioactive, biocompatible, biodegradable and good mechanical properties for clinical repair of damaged cartilage and bone tissue is a challenge of significant medical interest that remain to be achieved.

Bioactive Sr(II)/Chitosan/Poly(ε-caprolactone) Scaffolds for Craniofacial Tissue Regeneration. In Vitro and In Vivo Behavior.

In craniofacial tissue regeneration, the current gold standard treatment is autologous bone grafting, however, it presents some disadvantages. Although new alternatives have emerged there is still an urgent demand of biodegradable scaffolds to act as extracellular matrix in the regeneration process. A potentially useful element in bone regeneration is strontium. It is known to promote stimulation of osteoblasts while inhibiting osteoclasts resorption, leading to neoformed bone. The present paper reports the preparation and characterization of strontium (Sr) containing hybrid scaffolds formed by a matrix of ionically cross-linked chitosan and microparticles of poly(ε-caprolactone) (PCL). These scaffolds of relatively facile fabrication were seeded with osteoblast-like cells (MG-63) and human bone marrow mesenchymal stem cells (hBMSCs) for application in craniofacial tissue regeneration. Membrane scaffolds were prepared using chitosan:PCL ratios of 1:2 and 1:1 and 5 wt % Sr salts. Characterization was performed addressing physico-chemical properties, swelling behavior, in vitro biological performance and in vivo biocompatibility. Overall, the composition, microstructure and swelling degree (≈245%) of scaffolds combine with the adequate dimensional stability, lack of toxicity, osteogenic activity in MG-63 cells and hBMSCs, along with the in vivo biocompatibility in rats allow considering this system as a promising biomaterial for the treatment of craniofacial tissue regeneration.

Feasibility of ceramic-polymer composite cryogels as scaffolds for bone tissue engineering.

The purpose of the current study was to investigate whether the cryopolymerization technique is capable of producing suitable scaffolds for bone tissue engineering. Cryopolymers made of 2-hydroxyethyl methacrylate and acrylic acid with (W1 and W20) and without (W0) wollastonite particles were prepared. The elastic modulus of the specimens rose one order of magnitude from W1 to W20. Total porosity reached 56% for W0, 72% for W1 and 36% for W20, with pore sizes of up to 2 mm, large interconnection sizes of up to 1 mm and small interconnection sizes of 50-80 µm on dry specimens. Cryogels swell up to 224 ± 17% for W0, 315 ± 18% for W1 and 231 ± 27% for W20 specimens, while maintaining the integrity of the bodies. Pore sizes > 5 mm can be observed for swollen specimens. The biocompatibility of the samples was tested using human mesenchymal stem cells isolated from bone marrow and adipose tissues. Both types of cells attached and grew on the three tested substrates, colonized their inner regions and organized an extracellular cell matrix. Fibronectin and osteopontin levels decreased in the media from cells cultured on W20 samples, likely due to increased binding on the ECM deposited by cells. The osteoprotegerin-to-receptor activator of nuclear factor-κB ligand secretion ratios increased with increasing wollastonite content. Altogether, these results indicate that an appropriate balance of surface properties and structure that favours stromal cell colonization in the porous cryogels can be achieved by modulating the amount of wollastonite.