Alveolar bone loss: mechanisms, potential therapeutic targets, and interventions

Combination adipose-derived mesenchymal stem cells-demineralized dentin matrix increase bone marker expression in periodontitis rats

Background

Periodontal disease is common in both developed and developing countries and affects around 20-50% of the global population, especially in adolescents, adults and the elderly is a public health problem. ADMSCs have the advantage of regenerating damaged tissue with high quality. DDM in the form of slices can improve healing in the mandibular sockets of molar teeth. The combination of ADMSC-DDM is expected to accelerate bone regeneration.

Objectives

To analyze the combination of ADMSCs-DDM at increasing bone marker expression in periodontitis rats.

Methods

This research is experimental with a randomized control group post-test-only design. A total of 50 male Wistar rats were divided into four groups: 1) normal group (K); 2) CP model (K + ); 3) CP model and treated with DDM scaffold therapy (K(s)); 4) CP model and treated with ADMSCs-DDM combination therapy (K(sc)). Making a CP model with injected LPS P. gingivalis into interproximal gingiva of the right first and second lower molars. The in vivo research stage was the implantation of the DDM scaffold and the ADMSCs-DDM combination in the rat periodontal pocket. Rats were euthanized on days 7, 14, and 28, and immunohistochemistry of STRO-1, RUNX-2, OSX, COL-I, and OCN was performed. DDM scaffolds are made in 10%, 50% and 100% concentrations for MTT testing. Statistical results were analyzed with Kruskal-Wallis and Mann-Whitney tests.

Results

The results of the MTT scaffold DDM were significant in the 10%, 50%, and 100% dilution groups (p < 0.05). The results showed there was a substantial difference in the expression of STRO-1 between the study groups (p < 0.05). The (K(sc)) was significantly higher than the (K) in RUNX-2 expression (p < 0.05). OSX expression showed significant results between study groups (p < 0.05). The expression of OCN and COL-I showed a significant difference in all study groups on day 28, where the (K(sc)) was higher than the (K) (p < 0.05).

Conclusions

Administration of the ADMSCs-DDM combination can accelerate alveolar bone regeneration on day 28. There is a mechanism of alveolar bone regeneration through the STRO-1, RUNX-2, OSX, and the COL-I pathway in periodontitis models.

Association between chronic obstructive pulmonary disease and periodontal disease: a systematic review and meta-analysis

Objectives

Studies have suggested contradictory results on the relationship between chronic obstructive pulmonary disease (COPD) and periodontal disease (PD). The aim of this study was to determine whether PD increased the risk of COPD and COPD-related clinical events.

Design

A systematic review and meta-analysis.

Data sources

PubMed, Ovid EMBASE and Ovid CENTRAL were searched from inception to 22 February 2023.

Eligibility criteria for studies

We included trials and observational studies evaluating association of PD with the risk of COPD or COPD-related events (exacerbation and mortality), with statistical adjustment for smoking.

Data extraction and synthesis

Two investigators independently extracted data from selected studies using a standardised Excel file. Quality of studies was evaluated using the Newcastle-Ottawa Scale. OR with 95% CI was pooled in a random-effect model with inverse variance method.

Results

22 observational studies with 51 704 participants were included. Pooled analysis of 18 studies suggested that PD was weakly associated with the risk of COPD (OR: 1.20, 95% CI 1.09 to 1.32). However, in stratified and subgroup analyses, with strict adjustment for smoking, PD no longer related to the risk of COPD (adjusting for smoking intensity: OR: 1.14, 95% CI 0.86 to 1.51; smokers only: OR: 1.46, 95% CI 0.92 to 2.31; never smokers only: OR: 0.93, 95% CI 0.72 to 1.21). Moreover, PD did not increase the risk of COPD-related exacerbation or mortality (OR: 1.18, 95% CI 0.71 to 1.97) in the pooled result of four studies.

Conclusions

This study demonstrates PD confers no risk for COPD and COPD-related events when strictly adjusted by smoking. Large-scale prospective cohort studies with control of potential confounding factors are warranted to validate the present findings.

Nano-Based Drug Delivery Systems for Periodontal Tissue Regeneration

Periodontitis is a dysbiotic biofilm-induced and host-mediated inflammatory disease of tooth supporting tissues that leads to progressive destruction of periodontal ligament and alveolar bone, thereby resulting in gingival recession, deep periodontal pockets, tooth mobility and exfoliation, and aesthetically and functionally compromised dentition. Due to the improved biopharmaceutical and pharmacokinetic properties and targeted and controlled drug release, nano-based drug delivery systems have emerged as a promising strategy for the treatment of periodontal defects, allowing for increased efficacy and safety in controlling local inflammation, establishing a regenerative microenvironment, and regaining bone and attachments. This review provides an overview of nano-based drug delivery systems and illustrates their practical applications, future prospects, and limitations in the field of periodontal tissue regeneration.

Electrospun Nanofibers for Periodontal Treatment: A Recent Progress

Periodontitis is a major threat to oral health, prompting scientists to continuously study new treatment techniques. The nanofibrous membrane prepared via electrospinning has a large specific surface area and high porosity. On the one hand, electrospun nanofibers can improve the absorption capacity of proteins and promote the expression of specific genes. On the other hand, they can improve cell adhesion properties and prevent fibroblasts from passing through the barrier membrane. Therefore, electrospinning has unique advantages in periodontal treatment. At present, many oral nanofibrous membranes with antibacterial, anti-inflammatory, and tissue regeneration properties have been prepared for periodontal treatment. First, this paper introduces the electrospinning process. Then, the commonly used polymers of electrospun nanofibrous membranes for treating periodontitis are summarized. Finally, different types of nanofibrous membranes prepared via electrospinning for periodontal treatment are presented, and the future evolution of electrospinning to treat periodontitis is described.

Micro-Computed Tomography Analysis on Administration of Mesenchymal Stem Cells - Bovine Teeth Scaffold Composites for Alveolar Bone Tissue Engineering

The tissue engineering approach for periodontal tissue regeneration using a combination of stem cells and scaffold has been vastly developed. Mesenchymal Stem Cells (MSCs) seeded with Bovine Teeth Scaffold (BTSc) can repair alveolar bone damage in periodontitis cases. The alveolar bone regeneration process was analyzed by micro-computed tomography (µ-CT) to observe the structure of bone growth and to visualize the scaffold in 3-Dimensional (3D). The purpose of this study is to analyze alveolar bone regeneration by µ-CT following the combination of MSCs and bovine teeth scaffold (MSCs-BTSc) implantation in the Wistar rat periodontitis model. Methods. MSCs were cultured from adipose-derived mesenchymal stem cells of rats. BTSc was taken from bovine teeth and freeze-dried with a particle size of 150-355 µm. MSCs were seeded on BTSc for 24 hours and transplanted in a rat model of periodontitis. Thirty-five Wistar rats were made as periodontitis models with LPS induction from P. gingivalis injected to the buccal section of interproximal gingiva between the first and the second mandibular right-molar teeth for six weeks. There were seven groups (control group, BTSc group on day 7, BTSc group on day 14, BTSc group on day 28, MSCs-BTSc group on day 7, MSCs-BTSc group on day 14, MSCs-BTSc group on day 28). The mandibular alveolar bone was analyzed and visualized in 3D with µ-CT to observe any new bone growth. Statistical Analysis. Group data were subjected to the Kruskal Wallis test followed by the Mann-Whitney (p <0.05). The µ-CT qualitative analysis shows a fibrous structure, which indicates the existence of new bone regeneration. Quantitative analysis of the periodontitis model showed a significant difference between the control model and the model with the alveolar bone resorption (p <0.05). The bone volume and density measurements revealed that the MSCs-BTSc group on day 28 formed new bone compared to other groups (p <0.05). Administration of MSCs-BTSc combination has the potential to form new alveolar bone.

N-Acetyl-l-Leucine-Polyethyleneimine-Mediated Delivery of CpG Oligodeoxynucleotides 2006 Inhibits RAW264.7 Cell Osteoclastogenesis

INTRODUCTION

CpG oligodeoxynucleotides (CpG ODN) play important roles in resisting inflammation and bone resorption. However, the inherent instability and rapid degradation hinder their wider application. This study aimed to evaluate whether N-acetyl-L-leucine-modified polyethyleneimine (N-Ac-L-Leu-PEI) could effectively deliver CpG ODN 2006 to RAW264.7 cells and and if it can regulate osteoclastogenesis in vitro.

MATERIALS AND METHODS

Gel retardation assay was conducted to evaluate whether N- Ac-L-Leu-PEI and CpG ODN could form a stable complex. RAW264.7 cells were divided into four groups of control group, ODN group, phosphorothioate ODN group and N-Ac-L-Leu-PEI/ODN group. Fluorescence assay was conducted to evaluate the transfection rate of ODNs in different groups. Cell viability was determined by MTT assay. Cell apoptosis was determined by live-dead cell staining and flow cytometry assay. Relative expression levels of osteoclastic differentiation factors, including Nfatc, c-fos, receptor activator of nuclear factor κB (RANK), and matrix metalloproteinase 9 (MMP9), were determined by real-time PCR and Western blot.

RESULTS

N-Ac-L-Leu-PEI and CpG ODN could form a stable complex at a mass ratio of 1:1 (w:w). MTT assay showed that the cell viability of N-Ac-L-Leu-PEI was relatively high even at a mass ratio of 8 μg/mL. The transfection rate of N-Ac-L-Leu-PEI-ODN complex was higher than 90%. The cell proliferation and apoptosis was significantly enhanced in N-Ac-L-Leu-PEI- CpG ODN group when compared to those in phosphorothioate CpG ODN. The expression levels of Nfatc, c-fos, RANK, and MMP9 were significantly decreased in N-Ac-L-Leu-PEI/ODN complex group.

DISCUSSION

N-Ac-L-Leu-PEI could be a potential gene vehicle for the prevention of periodontitis-mediated bone resorption.

One-step treatment of periodontitis based on a core-shell micelle-in-nanofiber membrane with time-programmed drug release

As a chronic inflammatory disease, periodontitis is responsible for irreversible soft tissue damage and severe alveolar bone resorption. However, curative effects of current therapies are largely confined by the difficulty to simultaneously achieve anti-inflammation and bone regeneration. Also, the dynamic environment in oral cavity easily causes the drugs swallowed or rinsed away by saliva. We report here a one-step treatment based on a core-shell nanofiber membrane fabricated by coaxial electrospinning. Polymeric micelles containing SP600125 were distributed in the shell, while BMP-2 was incorporated in the core. After crosslinking, the nanofiber membrane displayed a prolonged degradation and release period up to 4 weeks. The release of SP600125 was detected at beginning, whereas BMP-2 was not released until day 12. Such a time-programmed release behavior was proved desirable for suppressing the expression of pro-inflammatory factors and enhancing the osteogenic induction in vitro. Further in vivo investigation confirmed that, by simply covering the periodontitis site with our nanofiber membrane, alveolar destruction was largely avoided and bone defects recovered within 2 month. Taken together, we believe that the use of our membrane with sequential release of SP600125 and BMP-2 may become a convenient and highly comprehensive therapy for periodontitis.

Granulocyte colony stimulating factor (G-CSF) regulates neutrophils infiltration and periodontal tissue destruction in an experimental periodontitis

Although granulocyte colony-stimulating factor(G-CSF) has pathogenic roles in several immune inflammatory diseases, its role in periodontitis has not been investigated. Here we detected local expression of G-CSF using public datasets in the Gene Expression Omnibus (GEO) database, and immune cell infiltration into gingival tissue was estimated based on single-sample gene set enrichment analysis (ssGSEA). G-CSF expression and neutrophil infiltration were also confirmed by human gingival biopsies analysis. Moreover, anti-G-CSF neutralizing antibody was locally administrated to investigate the effects of G-CSF neutralization on neutrophils infiltration and periodontal tissue destruction in periodontitis mice model. Two public datasets (GSE10334 and GSE16134), which included 424 patients with periodontitis and 133 health controls, were used in the analysis. Markedly increased immune cell infiltration and G-CSF expression in gingival tissues were found in the periodontitis group as compared to the control group. The higher expression of G-CSF was correlated with higher infiltration of immune cells, especially with neutrophil infiltration. Analysis of gingival biopsies further confirmed high neutrophil infiltration and G-CSF expression. In addition, anti-G-CSF antibody-treated mice with periodontitis showed significantly reduced alveolar bone resorption and neutrophil infiltration when compared with periodontitis mice treated with isotype control antibody. Also, anti-G-CSF antibody treatment significantly reduced mRNA expression of CXC chemokines (CXCL1, CXCL2 and CXCL3), interleukin 1β (IL-1β), IL-6, matrix metalloproteinases 9, receptor activator of nuclear factor κB ligand/osteoprotegerin (RANKL/OPG) ratio and osteoclasts number in periodontal tissues. In summary, neutrophil infiltration and G-CSF expression levels were significantly increased in inflamed gingival tissues. G-CSF neutralization in periodontal inflammation could alleviate neutrophil infiltration and periodontal tissue destruction in experimental periodontitis.

Dairy Food Consumption is Inversely Associated with the Prevalence of Periodontal Disease in Korean Adults

Dairy food consumption is known to be inversely associated with periodontal disease. However, there are conflicting results depending on the type of dairy foods. The aim of this study was to determine the relationship between individual dairy food consumption and periodontal disease. A total of 9798 Korean adults, aged ≥30 years, who participated in the fifth and sixth Korea National Health and Nutrition Examination Survey were included in this study’s analysis. Dairy food consumption was measured by the semi-quantitative food frequency questionnaire. Periodontal disease was defined as Community Periodontal Index score ≥3 in more than one of six sextants. Frequent intake of dairy foods (≥7 servings/week) was associated with a 24% lower prevalence of periodontal disease compared with never consumers after adjustment for age, gender, income, education, smoking, alcohol consumption, body mass index, diabetes mellitus status, calcium intake, tooth brushing frequency, and use of dental floss (Odds ratio (OR)= 0.76, 95% CI = 0.63–0.91, p for trend = 0.052). Also, frequent intake of milk (≥7 servings/week) was associated with a 26% lower prevalence of periodontal disease after adjustment for potential confounders (OR = 0.74, 95% CI = 0.61–0.89, p for trend = 0.022). Frequent consumption of dairy food including milk may have a beneficial effect on periodontal disease in the Korean adult population.

Functionalized nanoparticles containing MKP-1 agonists reduce periodontal bone loss

BACKGROUND

Progress over of the past several years has elucidated a role for mitogen-activated protein kinase phosphatase to regulate periodontal inflammation yielding new possibilities for treatment of periodontal diseases. These studies aimed to determine if nanoparticles (NPs) loaded with a pharmacological agent that induces mitogen-activated protein kinase phosphatase have potential clinical utility for management of periodontal inflammation and alveolar bone.

METHODS

Polyethylene glycol (PEG)-polylactide (PLA) (PEG-PLA) NPs were loaded with auranofin (ARN), an antirheumatic drug, to induce mitogen-activated protein kinase phosphatase (MKP)-1 expression in vitro and in vivo. Release kinetics of ARN from NPs was performed by high performance liquid chromatography (HPLC). Fluorescent-labeled NPs were used to show uptake into macrophages by flow cytometry. Real-time quantitative polymerase chain reaction (qPCR) was used to determine dual specificity protein phosphatase (Dusp)-1 mRNA induction by Auranofin-loaded nanoparticles (ARN-NPs) and viability of ARN-NPs was determined by colorimetric in vitro assays. Functional in vitro assays were used to measure functional MKP-1 induction and preclinical models using Aggregatibacter actinomycetemcomitans lipopolysaccharide-induced alveolar bone loss and microcomputed tomography was used to determine in vivo efficacy of functionalized ARN-NPs.

RESULTS

Data indicated that ARN-NPs had reduced cytotoxicity compared with free ARN and Dusp1 mRNA and MKP-1 activity was significantly increased by ARN-NPs in vitro. Flow cytometry indicated rapid uptake into macrophages. Finally, significant bone loss reduction was observed with ARN-NPs compared with control NPs in vivo using an lipopolysaccharide-induced rat model of periodontitis.

CONCLUSION

Results from these studies suggest that developing NPs functionalized with ARN have anti-inflammatory activities and may be a novel adjuvant therapeutic strategy to significantly improve periodontitis therapy and outcomes.

Bilateral maxillary augmentation using CAD/CAM manufactured allogenic bone blocks for restoration of congenitally missing teeth: A case report

OBJECTIVE

Various biomaterials have been successfully applied in alveolar bone regeneration, however, the reconstruction of extensive osseous defects remains challenging and is often unfeasible with granular grafting materials. Several studies have outlined allogenic bone blocks as valid alternative to autologous block grafting.

CLINICAL CONSIDERATIONS

In this report, we demonstrate the regeneration of two large osseous defects in the maxilla with allogenic bone blocks made from human donor bone. The bone blocks were customized using the CAD/CAM technology in order to enable the insertion of four dental implants.

CONCLUSIONS

Both blocks perfectly matched the defect geometry, showed limited resorption, led to the formation of sufficient amounts of mineralized bone in both horizontal and vertical dimensions and enabled the installation of implants according to the treatment plan. The implementation of innovative technologies for individualization of allogenic bone blocks simplifies the restoration of complex and extensive osseous defects and poses great benefits for both practitioners and patients.

CLINICAL SIGNIFICANCE

The here presented procedure demonstrates the successful regeneration of two extensive osseous defects in a patient suffering from hypodontia using two CAD/CAM manufactured allogenic bone blocks, rendering the procedure far less invasive as compared to guided bone regeneration carried out with autologous transplants. Furthermore, to the best of our knowledge, this is the first case report that radiographically demonstrates the new formation of a cortical bone layer following block grafting with solely cancellous bone blocks.

The Potential of Different Origin Stem Cells in Modulating Oral Bone Regeneration Processes

Tissue engineering has gained much momentum since the implementation of stem cell isolation and manipulation for regenerative purposes. Despite significant technical improvements, researchers still have to decide which strategy (which type of stem cell) is the most suitable for their specific purpose. Therefore, this short review discusses the advantages and disadvantages of the three main categories of stem cells: embryonic stem cells, mesenchymal stem cells and induced pluripotent stem cells in the context of bone regeneration for dentistry-associated conditions. Importantly, when deciding upon the right strategy, the selection needs to be made in concordance with the morbidity and the life-threatening level of the condition in discussion. Therefore, even when a specific type of stem cell holds several advantages over others, their availability, invasiveness of the collection method and ethical standards become deciding parameters.

Core-Shell Biphasic Microspheres with Tunable Density of Shell Micropores Providing Tailorable Bone Regeneration

IMPACT STATEMENT

We have developed the new core-shell bioceramic CSi-Sr4@CaP-px microspheres with tuning porous shell layer so that the biodegradation of both CSi-Sr4 core and CaP shell is readily adjusted synergistically. This is for the first time, to the best of our knowledge, that the bioceramic scaffolds concerning gradient distribution and microstructure-tailoring design is available for tailoring biodegradation and ion release (bioactivity) to optimizing osteogenesis. Furthermore, it is possibly helpful to develop new bioactive scaffold system for time-dependent tailoring bioactivity and microporous structure to significantly enhance bone regeneration and repair applications, especially in some non-load-bearing arbitrary 3D anatomical bone and teeth defects.

The antimicrobial peptide, human β-defensin-1, potentiates in vitro osteoclastogenesis via activation of the p44/42 mitogen-activated protein kinases

Previous studies have demonstrated increased expression and raised levels of human β-defensin (hBD)-1 in gingival tissue and crevicular fluid of patients with chronic periodontitis and peri-implantitis, oral bone-resorbing diseases caused by enhanced osteoclastogenesis. Therefore, we aimed to investigate the effect of hBD-1 on osteoclast formation and function and to elucidate the involved signaling pathway in vitro. Human peripheral blood mononuclear cells (PBMCs) were first incubated with various doses of hBD-1 and cell viability was assayed by MTT. PBMCs were treated with macrophage-colony stimulating factor and receptor activator of nuclear factor kappa-B ligand (RANKL) in the presence or absence of non-toxic doses of hBD-1. In vitro osteoclastogenesis was analyzed by tartrate-resistant acid phosphatase (TRAP) staining, osteoclast-specific gene expression, and a resorption pit assay. Involvement of mitogen-activated protein kinases (MAPKs) was studied by immunoblotting and specific MAPK inhibitors. HBD-1 potentiated induction of in vitro osteoclastogenesis by RANKL, as shown by significantly increased number of TRAP-positive multinuclear cells and resorption areas on the dentin slices, and further up-regulated expressions of osteoclast-specific genes compared to those by RANKL treatment (p <0.05). However, hBD-1 treatment without RANKL failed to induce formation of osteoclast-like cells. A significant and further increase in transient phosphorylation of the p44/42 MAPKs was demonstrated by hBD-1 co-treatment (p<0.05), consistent with the inhibitory effect by pretreatment with U0126 or PD98059 on hBD-1-enhanced osteoclastogenesis. Collectively, hBD-1 potentiates the induction of in vitro osteoclastogenesis by RANKL via enhanced phosphorylation of the p44/42 MAPKs.

Staphylococcal protein A promotes osteoclastogenesis through MAPK signaling during bone infection

Bone infection is a common and serious complication in the orthopedics field, which often leads to excessive bone destruction and non‐union. Osteoclast is the only type of cells which have the function of bone resorption. Its over activation is closely related to excessive bone loss. Staphylococcus aureus (S. aureus) is a major pathogen causing bone infection, which can produce a large number of strong pathogenic substances staphylococcal protein A (SPA). However, few studies were reported about the effects of SPA on osteoclastogenesis. In our study, we observed that S. aureus activated osteoclasts and promoted bone loss in bone infection specimens. Then, we investigated the effects of SPA on RANKL‐induced osteoclastogenesis in vitro, the results revealed that SPA promoted osteoclastic differentiation and fusion, and enhanced osteoclastic bone resorption. In addition, we also showed that SPA upregulated the expression of NFATc1 and c‐FOS through the activation of MAPK signaling to promote osteoclastogenesis. Our findings might help us better understand the pathogenic role of S. aureus in bone infection and develop new therapeutic strategies for infectious bone diseases.

[Effect of specific sequence oligodeoxynucleotide MT01 on the proliferation, apoptosis, and cell cycle of osteoblasts invaded by Porphyromonas gingivalis]

OBJECTIVE

This aimed to investigate the effect of specific sequence oligodeoxynucleotide MT01 on the biological properties of osteoblasts invaded by Porphyromonas gingivalis (P. gingivalis ) by evaluating proliferation, cell cycle, and apoptosis.

METHODS

MG63 osteoblasts were recovered and incubated with MT01, CpG ODN, metronidazole (MNZ), and gentamicin (GEN) for 3 h. P. gingivalis (the multiplicity of infection was 100:1) was added subsequently and cocultured for another 24 and 48 h. Cells with PBS comprised the blank group, whereas cells with P. gingivalis comprised the negative controls. Six experimental groups were established: PBS group, P. gingivalis group, MT01+P. gingivalis group, CpG ODN+ P. gingivalis group, MNZ+P. gingivalis group, and GEN+P. gingivalis group. The proliferative ability was measured by methyl thiazolyl tetrazolium assay, and the percentages of apoptosis and cell cycle were examined by flow cytometry.

RESULTS

Compared with the blank group, proliferation increased significantly in the MT01+P. gingivalis group (P < 0.05). The ratio of cells was lower at the G₁ phase and higher at the S phase in the MT01+P. gingivalis group compared with the results in the P. gingivalis group (P < 0.05). Early cell apoptosis in the MT01+P. gingivalis group was significantly lower than that in the P. gingivalis group (P < 0.05).

CONCLUSION

MT01 can promote the proliferation, reduce the ratio of the G₁phase, increase the ratio of the S phase, and inhibit the early apoptosis of osteoblasts invaded by P. gingivalis.

Regulators of G-protein-signaling proteins: negative modulators of G-protein-coupled receptor signaling

Regulators of G-protein-signaling (RGS) proteins are a category of intracellular proteins that have an inhibitory effect on the intracellular signaling produced by G-protein-coupled receptors (GPCRs). RGS along with RGS-like proteins switch on through direct contact G-alpha subunits providing a variety of intracellular functions through intracellular signaling. RGS proteins have a common RGS domain that binds to G alpha. RGS proteins accelerate GTPase and thus enhance guanosine triphosphate hydrolysis through the alpha subunit of heterotrimeric G proteins. As a result, they inactivate the G protein and quickly turn off GPCR signaling thus terminating the resulting downstream signals. Activity and subcellular localization of RGS proteins can be changed through covalent molecular changes to the enzyme, differential gene splicing, and processing of the protein. Other roles of RGS proteins have shown them to not be solely committed to being inhibitors but behave more as modulators and integrators of signaling. RGS proteins modulate the duration and kinetics of slow calcium oscillations and rapid phototransduction and ion signaling events. In other cases, RGS proteins integrate G proteins with signaling pathways linked to such diverse cellular responses as cell growth and differentiation, cell motility, and intracellular trafficking. Human and animal studies have revealed that RGS proteins play a vital role in physiology and can be ideal targets for diseases such as those related to addiction where receptor signaling seems continuously switched on.