Blood absorption capacity of different xenograft bone substitutes. An in-vitro study

Commercially available xenograft blocks, claim to have adequate characteristics to interact with biological media and thus permitting biological fluid absorption. The objective of this in vitro study was to compare the blood absorption capacity of four different xenograft block materials of different composition of collagen and porosity. Four brands of xenograft block materials were used (NuOss®, Bio-Oss®, Osteobiol® and Smartbone®). Five samples of each brand were analyzed, making a total of 20 tests. Human blood was used as the absorption liquid for the present experiment. The time period, in which the block remains in contact with the blood, was registered at 30 seconds (T1), 60 seconds (T2) and 5 minutes (T3). The xenograft blocks were evaluated according to their absorption capacity. The absorption capacity of the different biomaterials were statistical significant different (p<0,001) at T1, T2 and T3 time points. At 30 seconds, Smartbone® absorbed significantly less blood than NuOss® and Bio-Oss®, however, without differences comparing with Osteobiol®. The NuOss®, Bio-Oss® and Osteobiol® did not register any significant difference between them. At 60 seconds, the Smartbone® absorbed significantly less blood than the other biomaterials. The NuOss® was significantly superior than Osteobiol®, but without differences relatively with Bio-Oss®. Also the Bio-Oss® and Osteobiol® did not register any difference between them. At 5 minutes, the Smatbone® continued to significantly absorbed less blood than any other biomaterial, nevertheless, NuOss®, Bio-Oss® and Osteobiol® not register again any significant difference between them. Despite of small sample size, it can be concluded that NuOss® was superior, in terms of blood absorption capacity, comparing with the other block biomaterials at 30 seconds, 60 seconds and 5 minutes. However, more investigation in a clinical setting are needed to know the clinical implications of the absorption capacity of such biomaterials

Palatal fibroblasts reduce osteoclastogenesis in murine bone marrow cultures.

BACKGROUND Preclinical studies support the assumption that connective tissue grafts preserve the alveolar bone from resorption; the underlying cellular mechanisms, however, remain unknown. The cellular mechanisms may be attributed to the paracrine activity of the palatal fibroblasts. It was thus reasonable to suggest that palatal connective tissue grafts reduce the formation of osteoclasts. METHODS To test this hypothesis, human palatal fibroblasts were examined for their capacity to modulate the formation of osteoclasts in murine bone marrow cultures exposed to RANKL, M-CSF and TGF-β1. Osteoclastogenesis was determined by tartrate-resistant acid phosphatase (TRAP) staining and gene expression analysis. The formation of antigen presenting cells was based on the expression of CD14 and costimmulatory molecules of antigen presenting cells. The paracrine interaction of fibroblasts and the bone marrow was modeled in vitro with inserts of cell-occlusive membranes. RESULTS In cocultures without cell-to-cell contact, palatal fibroblasts caused a decrease in the expression of the osteoclast marker genes in bone marrow cells; calcitonin receptors, cathepsin K, TRAP, and osteoclast-associated receptor. Also the number of TRAP positive multinucleated cells was decreased in the presence of fibroblasts. Notably, palatal fibroblasts increased the expression of CD14 and the co-stimulatory proteins CD40, CD80, and CD86 in bone marrow cells. Bone marrow cells had no considerable impact on fibroblast viability and proliferation marker genes. With regard to cell distribution, osteoclasts were most prominent in the center of the membranes, while fibroblasts accumulated immediately adjacent to the border of the insert forming a ring-like structure on the surface of the culture plate. CONCLUSION The data suggest that palatal fibroblasts provide a paracrine environment that reduces osteoclastogenesis and increases markers of antigen presenting cells. Morover, the paracrine model revealed a joint activity between palatal fibroblasts and bone marrow cells visualized by the characteristic cell distribution in the two separated compartments

Bone conditioned media (BCM) improves osteoblast adhesion and differentiation on collagen barrier membranes

Background: The use of autogenous bone chips during guided bone regeneration procedures has remained the gold standard for bone grafting due to its excellent combination of osteoconduction, osteoinduction and osteogenesis. Recent protocols established by our group have characterized specific growth factors and cytokines released from autogenous bone that have the potential to be harvested and isolated into bone conditioned media (BCM). Due to the advantageous osteo-promotive properties of BCM, the aims of the present study was to pre-coat collagen barrier membranes with BCM and investigate its effect on osteoblast adhesion, proliferation and differentiation for possible future clinical use. Methods: Scanning electron microscopy (SEM) was first used to qualitative assess BCM protein accumulation on the surface of collagen membranes. Thereafter, undifferentiated mouse ST2 stromal bone marrow cells were seeded onto BioGide porcine derived collagen barrier membranes (control) or barrier membranes pre-coated with BCM (test group). Control and BCM samples were compared for cell adhesion at 8 h, cell proliferation at 1, 3 and 5 days and real-time PCR at 5 days for osteoblast differentiation markers including Runx2, alkaline phosphatase (ALP), osteocalcin (OCN) and bone sialoprotein (BSP). Mineralization was further assessed with alizarin red staining at 14 days post seeding. Results: SEM images demonstrated evidence of accumulated proteins found on the surface of collagen membranes following coating with BCM. Analysis of total cell numbers revealed that the additional pre-coating with BCM markedly increased cell attachment over 4 fold when compared to cells seeded on barrier membranes alone. No significant difference could be observed for cell proliferation at all time points. BCM significantly increased mRNA levels of osteoblast differentiation markers including ALP, OCN and BSP at 5 days post seeding. Furthermore, barrier membranes pre-coated with BCM demonstrated a 5-fold increase in alizarin red staining at 14 days. Conclusion: The results from the present study suggest that the osteoconductive properties of porcine-derived barrier membranes could be further improved by BCM by significantly increasing cell attachment, differentiation and mineralization of osteoblasts in vitro. Future animal testing is required to fully characterize the additional benefits of BCM for guided bone regeneration

On the search of the ideal barrier membrane for guided bone regeneration

GBRs are essential procedures in implant dentistry and periodontology where barrier membranes play an important role by isolating soft tissue and allowing bone to grow. Not all membranes function the same way, as they differ from their origin and structure, it is important to understand how membranes behave and differ one from others in order to achieve a predictable treatment. A systematic search on Medline by two independent reviewers was performed for articles published until July 2017 reporting the characteristics or properties of barrier membranes. The question that preceded the search was designed according to PICO rules. A total of 124 articles were initially identified from electronic searching. After abstract/full-text review, 21 were included for a systematic review. According to the extracted data and article analysis, barrier membranes should fulfill the following criteria in order to success: biocompatibility, space maintaining, occlusive function, easy - handling and a bioactivation friendly property. With the development of new biomaterials and surfaces, a great advance in this area is expected. It has been clearly described that biocompatibility is the most important requirement to take into account when choosing a membrane, but other factors such as space maintaining capacity, cell oclusiveness, easy handling and bioactivation friendly materials are the ones that will fulfill our necessities

TGF-βRI kinase activity mediates Emdogain-stimulated in vitro osteoclastogenesis

Objectives: Emdogain, containing an extract of fetal porcine enamel matrix proteins, is a potent stimulator of in vitro osteoclastogenesis. The underlying molecular mechanisms are, however, unclear. Material and methods: Here, we have addressed the role of transforming growth factor-beta receptor type 1 (TGF-βRI) kinase activity on osteoclastogenesis in murine bone marrow cultures. Results: Inhibition of TGF-βRI kinase activity with SB431542 abolished the effect of Emdogain on osteoclastogenesis induced by receptor activator of nuclear factor kappa-B ligand or tumor necrosis factor-alpha. SB431542 also suppressed the Emdogain-mediated increase of OSCAR, a co-stimulatory protein, and dendritic cell-specific transmembrane protein and Atp6v0d2, the latter two being involved in cell fusion. Similar to transforming growth factor-beta1 (TGF-β), Emdogain could not compensate for the inhibition of IL-4 and IFNγ on osteoclast formation. When using the murine macrophage cell line RAW246.7, SB431542 and the smad-3 inhibitor SIS3 blocked Emdogain-stimulated expression of the transcription factor NFATc1. Conclusions: Taken together, the data suggest that TGF-βRI kinase activity is necessary to mediate in vitro effects of Emdogain on osteoclastogenesis. Clinical relevance: Based on these in vitro data, we can speculate that at least part of the clinical effects of Emdogain on osteoclastogenesis is mediated via TGF-β signaling

Bone conditioned media (BCM) improves osteoblast adhesion and differentiation on collagen barrier membranes.

BACKGROUND The use of autogenous bone chips during guided bone regeneration procedures has remained the gold standard for bone grafting due to its excellent combination of osteoconduction, osteoinduction and osteogenesis. Recent protocols established by our group have characterized specific growth factors and cytokines released from autogenous bone that have the potential to be harvested and isolated into bone conditioned media (BCM). Due to the advantageous osteo-promotive properties of BCM, the aims of the present study was to pre-coat collagen barrier membranes with BCM and investigate its effect on osteoblast adhesion, proliferation and differentiation for possible future clinical use. METHODS Scanning electron microscopy (SEM) was first used to qualitative assess BCM protein accumulation on the surface of collagen membranes. Thereafter, undifferentiated mouse ST2 stromal bone marrow cells were seeded onto BioGide porcine derived collagen barrier membranes (control) or barrier membranes pre-coated with BCM (test group). Control and BCM samples were compared for cell adhesion at 8 h, cell proliferation at 1, 3 and 5 days and real-time PCR at 5 days for osteoblast differentiation markers including Runx2, alkaline phosphatase (ALP), osteocalcin (OCN) and bone sialoprotein (BSP). Mineralization was further assessed with alizarin red staining at 14 days post seeding. RESULTS SEM images demonstrated evidence of accumulated proteins found on the surface of collagen membranes following coating with BCM. Analysis of total cell numbers revealed that the additional pre-coating with BCM markedly increased cell attachment over 4 fold when compared to cells seeded on barrier membranes alone. No significant difference could be observed for cell proliferation at all time points. BCM significantly increased mRNA levels of osteoblast differentiation markers including ALP, OCN and BSP at 5 days post seeding. Furthermore, barrier membranes pre-coated with BCM demonstrated a 5-fold increase in alizarin red staining at 14 days. CONCLUSION The results from the present study suggest that the osteoconductive properties of porcine-derived barrier membranes could be further improved by BCM by significantly increasing cell attachment, differentiation and mineralization of osteoblasts in vitro. Future animal testing is required to fully characterize the additional benefits of BCM for guided bone regeneration

Comparison of resistive capacitive energy transfer therapy on cadaveric molars and incisors with and without implants.

Capacitive-resistive energy transfer therapy (CRet) is used to improve the rehabilitation of different injuries. This study aimed to evaluate and compare the changes in temperature and current flow during different CRet applications on upper and lower molars and incisors, with and without implants, on ten cryopreserved corpses. Temperatures were taken on molars and incisors with invasive devices and skin temperature was taken with a digital thermometer at the beginning and after treatments. Four interventions: 15 VA capacitive hypothermic (CAPH), 8 watts resistive (RES8), 20 watts resistive (RES20) and 75 VA capacitive (CAP75) were performed for 5 min each. All treatments in this study generated current flow (more than 0.00005 A/m2) and did not generate a significant temperature increase (p > 0.05). However, RES20 application slightly increased surface temperature on incisors without implants (p = 0.010), and molar with (p = 0.001) and without implant (p = 0.008). Also, CAP75 application increased surface temperature on molars with implant (p = 0.002) and upper incisor with implant (p = 0.001). In conclusion, RES8 and CAPH applications seem to be the best options to achieve current flow without an increase in temperature on molars and incisors with and without implants

In vitro study of osteoclastogenesis under simulated bone augmentation: The effects of bone-conditioned medium and saliva on osteoclastogenesis

The present PhD thesis is a compendium of four publications broadening the knowledge on osteoclastogenesis under simulated bone augmentation, more especially about the effects of saliva and bone-conditioned medium on osteoclastogenesis. Resorption of bone grafts and host bone, can be a challenge especially when a bonny defect has to be regenerated or there is a lack of host bone due to a trauma, pathology, aging or tooth extraction among others. In the oral cavity, saliva is present and can reach mineralized surfaces, however, the relationship between saliva and bone resorption is yet unknown. Herein, we examined whether saliva affects the process of osteoclastogenesis in vitro, possibly affecting bone healing and bone regeneration. Bone regeneration is a common procedure in traumatology, periodontology, oral and maxillofacial surgery that involves the use of bone fillers. Bone autograft is considered to be the gold standard bone substitute due to its trinity of properties: osteoinductivity, osteoconductivity and osteogenesis. Paracrine factors released from bone autografts might contribute to the overall process of graft consolidation, however the underlying mechanisms are unknown. Here, we determined the protein spectrum released from porcine bone chips into the conditioned medium (BCM) to mimic the paracrine environment of cortical bone grafts. Some of the factors released by bone autografts could maybe influence on the autograft resorption and therefore explain why osteoclasts rapidly form on the surface of bone chips at augmentation sites. The underlying molecular mechanism, however, is unclear. Soluble factors released from bone chips in vitro have a robust impact on mesenchymal cell differentiation. Here we determined whether these soluble factors change the differentiation of hematopoietic cells into osteoclasts, still unknown. Based on the in vitro results here presented, it can be observed that saliva suppresses osteoclastogenesis and leads to the development of a phagocytic cell phenotype, therefore affecting function of osteoclasts, the bone resorbing cells. Resorption of bone autografts could be attributed to some of the proteins detected on the secretions of bone autografts, termed bone conditioned medium (BCM). Proteomic analysis showed that BCM contains more than 150 proteins, among which, 43 were categorized into “secreted” and “extracellular matrix”. We discovered growth factors that are not only detectable in BCM, but potentially also target cellular processes involved in bone regeneration e.g. pleiotrophin, galectin-1, TGF-β-induced gene (TGFBI), latency-associated peptide forming a complex with TGF-β1, and TGF-β2. Results here presented on the influence of BCM on osteoclastogenesis demonstrated that activated BCM by heat is able to stimulate osteoclastogenesis in vitro. These in vitro results support the notion that the resorption of autografts may be supported by as yet less defined regulatory mechanisms. Moreover the presented protocols on the use of BCM should encourage to further reveal the paracrine effects of bone grafts during bone regeneration and open a path for translational research in the broad field of reconstructive surgery. Taking everything together, it can be concluded that saliva affects bone resorption towards the development of a phagocytic cell line, and that not only saliva affects bone resorption but also the secretions from autologous bone grafts. There is enough evidence to conclude that bone autografts not only have three properties, but one more: a regulation property, the fourth dimension of autologous bone grafts.La present tesis doctoral és un compendi de quatre publicacions ampliant el coneixement de l’osteoclastogènesis en les regeneracions òssies, més especialment sobre els efectes de la saliva i el medi condicionat ossi en l’osteoclastogènesis. La reabsorció dels empelts ossis i de l’os de l’hoste, pot ser un repte especialment quan un defecte ossi ha de ser regenerat en condicions desfavorables o grans atròfies com per exemple després de traumatismes, diverses patologies, edat avançada o extraccions múlti¬ples. En la cavitat oral, la saliva pot entrar en contacte amb superfícies mineralitzades, tot i això la relació entre saliva i reabsorció òssia és encara desconeguda. En la present tesis hem examinat si la saliva afecta el procés de l’osteoclastogènesis in vitro, possiblement afectant a la regeneració i cicatrització òssia. La regeneració òssia és un procés comú en traumatolo¬gia, periodòncia, cirurgia oral i maxil•lofacial que involucra l’ús de substituts ossis. Els empelts d’os autòleg són considerats l’estàndard d’or dels sub¬stituts ossis degut a la seva trinitat de propietats: osteoconductivitat, oste¬oinducció i osteogènesis. Els factors paracrins alliberats pels empelts d’os autòleg podrien contribuir en el conjunt de processos que donen com a re-sultat la consolidació del empelts, tanmateix els mecanismes que regeixen aquest processos no són coneguts. En el present treball hem pogut carac¬teritzar un conjunt de proteïnes alliberades per partícules d’os cortical porcí en el medi condicionat ossi (BCM) per imitar l’ambient paracrí dels em¬pelts d’os cortical. Alguns dels factors alliberats pels empelts d’os autòleg podrien influenciar la reabsorció òssia explicant per què els osteoclasts es formen ràpidament a la superfície de les partícules d’os autòleg en els llocs regenerats. Tot i això els mecanismes moleculars que regeixen aquest pro¬cés, encara son desconeguts. Factors solubles alliberats pels empelts d’os autòleg in vitro tenen un impacte robust a la diferenciació de cèl•lules mes¬enquimals. En la present tesis doctoral, hem determinat si aquests factors solubles son capaços de canviar la diferenciació de cèl•lules mare hemat¬opoètiques a osteoclasts, desconegut abans de realitzar els estudis aquí presentats. Basant-nos en els resultats in vitro aquí presentats, es pot observar que la saliva suprimeix l’osteoclastogènesis i promociona el desenvolupament de cèl•lules amb un fenotip fagocític, afectant a la funció dels osteoclasts, les cèl•lules encarregades de reabsorbir l’os. La reabsorció dels empelts d’os autòleg es pot atribuir a l’efecte d’algunes de les proteïnes detecta¬des en les secrecions dels auto-empelts, anomenant aquestes secrecions Medi Condicionat d’Os (BCM). Un estudi proteòmic del BCM va mostrar que aquest medi condicionat conté més de 150 proteïnes, de les quals 43 es van caracteritzar com “secretades” i presents en la matriu extracel•lular. Vàrem descobrir que alguns dels factors continguts en el BCM com per exemple pleiotropina, galectina-1 o TGF-β1 poden afectar processos cel•lulars involucrats en la regeneració òssia. El resultats presentats en aquesta tesis sobre l’influencia del BCM en l’osteoclastogènesis demostra que el BCM termo-activat és capaç d’estimular l’osteoclastogènesis in vitro. Aquests resultats in vitro suporten la noció que la reabsorció dels auto-empelts ossis pot ser que estigui estimulada per mecanismes reguladors encara no definits. En aquesta línia, els protocols presentats sobre l’ús del BCM haurien d’animar a revelar els efectes paracrins dels empelts d’os autòleg durant el procés de regeneració òssia i obrir nous camins a investi¬gacions translacionals en l’ampli camp de la cirurgia reconstructora. Resumint-ho tot, podem concloure que la saliva afecta la reabsorció òssia promocionant el desenvolupament de cèl•lules amb un fenotip fagocític, i que no només la saliva pot afectar a la reabsorció òssia, sinó que també les se¬crecions dels injerts d’os autòleg. En aquest punt, hi ha suficient evidencia per concloure que els auto-empelts d’os no només tenen tres propietats, sinó una més: la propietat reguladora, la quarta dimensió dels empelts d’os autòleg

In vitro study of osteoclastogenesis under simulated bone augmentation: The effects of bone-conditioned medium and saliva on osteoclastogenesis

The present PhD thesis is a compendium of four publications broadening the knowledge on osteoclastogenesis under simulated bone augmentation, more especially about the effects of saliva and bone-conditioned medium on osteoclastogenesis. Resorption of bone grafts and host bone, can be a challenge especially when a bonny defect has to be regenerated or there is a lack of host bone due to a trauma, pathology, aging or tooth extraction among others. In the oral cavity, saliva is present and can reach mineralized surfaces, however, the relationship between saliva and bone resorption is yet unknown. Herein, we examined whether saliva affects the process of osteoclastogenesis in vitro, possibly affecting bone healing and bone regeneration. Bone regeneration is a common procedure in traumatology, periodontology, oral and maxillofacial surgery that involves the use of bone fillers. Bone autograft is considered to be the gold standard bone substitute due to its trinity of properties: osteoinductivity, osteoconductivity and osteogenesis. Paracrine factors released from bone autografts might contribute to the overall process of graft consolidation, however the underlying mechanisms are unknown. Here, we determined the protein spectrum released from porcine bone chips into the conditioned medium (BCM) to mimic the paracrine environment of cortical bone grafts. Some of the factors released by bone autografts could maybe influence on the autograft resorption and therefore explain why osteoclasts rapidly form on the surface of bone chips at augmentation sites. The underlying molecular mechanism, however, is unclear. Soluble factors released from bone chips in vitro have a robust impact on mesenchymal cell differentiation. Here we determined whether these soluble factors change the differentiation of hematopoietic cells into osteoclasts, still unknown. Based on the in vitro results here presented, it can be observed that saliva suppresses osteoclastogenesis and leads to the development of a phagocytic cell phenotype, therefore affecting function of osteoclasts, the bone resorbing cells. Resorption of bone autografts could be attributed to some of the proteins detected on the secretions of bone autografts, termed bone conditioned medium (BCM). Proteomic analysis showed that BCM contains more than 150 proteins, among which, 43 were categorized into “secreted” and “extracellular matrix”. We discovered growth factors that are not only detectable in BCM, but potentially also target cellular processes involved in bone regeneration e.g. pleiotrophin, galectin-1, TGF-β-induced gene (TGFBI), latency-associated peptide forming a complex with TGF-β1, and TGF-β2. Results here presented on the influence of BCM on osteoclastogenesis demonstrated that activated BCM by heat is able to stimulate osteoclastogenesis in vitro. These in vitro results support the notion that the resorption of autografts may be supported by as yet less defined regulatory mechanisms. Moreover the presented protocols on the use of BCM should encourage to further reveal the paracrine effects of bone grafts during bone regeneration and open a path for translational research in the broad field of reconstructive surgery. Taking everything together, it can be concluded that saliva affects bone resorption towards the development of a phagocytic cell line, and that not only saliva affects bone resorption but also the secretions from autologous bone grafts. There is enough evidence to conclude that bone autografts not only have three properties, but one more: a regulation property, the fourth dimension of autologous bone grafts.La present tesis doctoral és un compendi de quatre publicacions ampliant el coneixement de l’osteoclastogènesis en les regeneracions òssies, més especialment sobre els efectes de la saliva i el medi condicionat ossi en l’osteoclastogènesis. La reabsorció dels empelts ossis i de l’os de l’hoste, pot ser un repte especialment quan un defecte ossi ha de ser regenerat en condicions desfavorables o grans atròfies com per exemple després de traumatismes, diverses patologies, edat avançada o extraccions múlti¬ples. En la cavitat oral, la saliva pot entrar en contacte amb superfícies mineralitzades, tot i això la relació entre saliva i reabsorció òssia és encara desconeguda. En la present tesis hem examinat si la saliva afecta el procés de l’osteoclastogènesis in vitro, possiblement afectant a la regeneració i cicatrització òssia. La regeneració òssia és un procés comú en traumatolo¬gia, periodòncia, cirurgia oral i maxil•lofacial que involucra l’ús de substituts ossis. Els empelts d’os autòleg són considerats l’estàndard d’or dels sub¬stituts ossis degut a la seva trinitat de propietats: osteoconductivitat, oste¬oinducció i osteogènesis. Els factors paracrins alliberats pels empelts d’os autòleg podrien contribuir en el conjunt de processos que donen com a re-sultat la consolidació del empelts, tanmateix els mecanismes que regeixen aquest processos no són coneguts. En el present treball hem pogut carac¬teritzar un conjunt de proteïnes alliberades per partícules d’os cortical porcí en el medi condicionat ossi (BCM) per imitar l’ambient paracrí dels em¬pelts d’os cortical. Alguns dels factors alliberats pels empelts d’os autòleg podrien influenciar la reabsorció òssia explicant per què els osteoclasts es formen ràpidament a la superfície de les partícules d’os autòleg en els llocs regenerats. Tot i això els mecanismes moleculars que regeixen aquest pro¬cés, encara son desconeguts. Factors solubles alliberats pels empelts d’os autòleg in vitro tenen un impacte robust a la diferenciació de cèl•lules mes¬enquimals. En la present tesis doctoral, hem determinat si aquests factors solubles son capaços de canviar la diferenciació de cèl•lules mare hemat¬opoètiques a osteoclasts, desconegut abans de realitzar els estudis aquí presentats. Basant-nos en els resultats in vitro aquí presentats, es pot observar que la saliva suprimeix l’osteoclastogènesis i promociona el desenvolupament de cèl•lules amb un fenotip fagocític, afectant a la funció dels osteoclasts, les cèl•lules encarregades de reabsorbir l’os. La reabsorció dels empelts d’os autòleg es pot atribuir a l’efecte d’algunes de les proteïnes detecta¬des en les secrecions dels auto-empelts, anomenant aquestes secrecions Medi Condicionat d’Os (BCM). Un estudi proteòmic del BCM va mostrar que aquest medi condicionat conté més de 150 proteïnes, de les quals 43 es van caracteritzar com “secretades” i presents en la matriu extracel•lular. Vàrem descobrir que alguns dels factors continguts en el BCM com per exemple pleiotropina, galectina-1 o TGF-β1 poden afectar processos cel•lulars involucrats en la regeneració òssia. El resultats presentats en aquesta tesis sobre l’influencia del BCM en l’osteoclastogènesis demostra que el BCM termo-activat és capaç d’estimular l’osteoclastogènesis in vitro. Aquests resultats in vitro suporten la noció que la reabsorció dels auto-empelts ossis pot ser que estigui estimulada per mecanismes reguladors encara no definits. En aquesta línia, els protocols presentats sobre l’ús del BCM haurien d’animar a revelar els efectes paracrins dels empelts d’os autòleg durant el procés de regeneració òssia i obrir nous camins a investi¬gacions translacionals en l’ampli camp de la cirurgia reconstructora. Resumint-ho tot, podem concloure que la saliva afecta la reabsorció òssia promocionant el desenvolupament de cèl•lules amb un fenotip fagocític, i que no només la saliva pot afectar a la reabsorció òssia, sinó que també les se¬crecions dels injerts d’os autòleg. En aquest punt, hi ha suficient evidencia per concloure que els auto-empelts d’os no només tenen tres propietats, sinó una més: la propietat reguladora, la quarta dimensió dels empelts d’os autòleg

Tissue Integration and Degradation of a Porous Collagen-Based Scaffold Used for Soft Tissue Augmentation.

Collagen-based scaffolds hold great potential for tissue engineering, since they closely mimic the extracellular matrix. We investigated tissue integration of an engineered porous collagen-elastin scaffold developed for soft tissue augmentation. After implantation in maxillary submucosal pouches in 6 canines, cell invasion (vimentin), extracellular matrix deposition (collagen type I) and scaffold degradation (cathepsin k, tartrate-resistant acid phosphatase (TRAP), CD86) were (immuno)-histochemically evaluated. Invasion of vimentin+ cells (scattered and blood vessels) and collagen type I deposition within the pores started at 7 days. At 15 and 30 days, vimentin+ cells were still numerous and collagen type I increasingly filled the pores. Scaffold degradation was characterized by collagen loss mainly occurring around 15 days, a time point when medium-sized multinucleated cells peaked at the scaffold margin with simultaneous labeling for cathepsin k, TRAP, and CD86. Elastin was more resistant to degradation and persisted up to 90 days in form of packages well-integrated in the newly formed soft connective tissue. In conclusion, this collagen-based scaffold maintained long-enough volume stability to allow an influx of blood vessels and vimentin+ fibroblasts producing collagen type I, that filled the scaffold pores before major biomaterial degradation and collapse occurred. Cathepsin k, TRAP and CD86 appear to be involved in scaffold degradation