Cell Therapy Based on Gingiva-Derived Mesenchymal Stem Cells Seeded in a Xenogeneic Collagen Matrix for Root Coverage of RT1 Gingival Lesions: An In Vivo Experimental Study.

(1) Background: To investigate the effect of a xenogeneic collagen matrix (CMX) seeded with autologous gingiva-derived mesenchymal cells (GMSCs) when combined with a coronally advanced flap (CAF) in the treatment of localized gingival recession type 1 (RT1). (2) Methods: Dehiscence-type defects were created in seven dogs. GMSCs were isolated, transfected with a vector carrying green fluorescent protein (GFP) and expanded. Once chronified, the defects were randomly treated with (1) CAF plus the combination of CMX and GFP+ GMSCs, (2) CAF plus CMX with autologous fibroblasts, (3) CAF plus CMX and (4) CAF alone. Histological and clinical outcomes at 2- and 6-week healing periods were analyzed and compared among groups. (3) Results: Histologically, the addition of autologous cells to the CMX resulted in reduced inflammation and a variable degree of new cementum/bone formation. CMX plus GMSCs resulted in greater mean recession reduction (1.42; SD = 1.88 mm) and percentage of teeth with recession reduction of ≥2 mm (57%) when compared to the other groups, although these differences were not statistically significant. (4) Conclusions: The histometric and clinical results indicated a positive trend favouring the combination of CMX and GMSCs with the CAF when compared to the groups without cells, although these differences were not statistically significant.

Periodontal regeneration using a xenogeneic bone substitute seeded with autologous periodontal ligament-derived mesenchymal stem cells: A 12-month quasi-randomized controlled pilot clinical trial.

AIM: To evaluate the safety and efficacy of autologous periodontal ligament-derived mesenchymal stem cells (PDL-MSCs) embedded in a xenogeneic bone substitute (XBS) for the regenerative treatment of intra-bony periodontal defects. MATERIAL AND METHODS: This quasi-randomized controlled pilot phase II clinical trial included patients requiring a tooth extraction and presence of one intra-bony lesion (1-2 walls). Patients were allocated to either the experimental (XBS + 10 × 106 PDL-MSCs/100 mg) or the control group (XBS). Clinical and radiographical parameters were recorded at baseline, 6, 9 and 12 months. The presence of adverse events was also evaluated. Chi-square, Student's t test, Mann-Whitney U, repeated-measures ANOVA and regression models were used. RESULTS: Twenty patients were included. No serious adverse events were reported. Patients in the experimental group (n = 9) showed greater clinical attachment level (CAL) gain (1.44, standard deviation [SD] = 1.87) and probing pocket depth (PPD) reduction (2.33, SD = 1.32) than the control group (n = 10; CAL gain = 0.88, SD = 1.68, and PPD reduction = 2.10, SD = 2.46), without statistically significant differences. CONCLUSION: The application of PDL-MSCs to XBS for the treatment of one- to two-wall intra-bony lesions was safe and resulted in low postoperative morbidity and appropriate healing, although its additional benefit, when compared with the XBS alone, was not demonstrated.

Cell therapy with allogenic canine periodontal ligament-derived cells in periodontal regeneration of critical size defects.

AIM: The objective of this in vivo experimental study to evaluate the regenerative potential of a cell therapy combining allogenic periodontal ligament-derived cells within a xenogeneic bone substitute in a similar experimental model. METHODS: In nine beagle dogs, critical size 6-mm supra-alveolar periodontal defects were created around the PIII and PIV. The resulting supra-alveolar defects were randomly treated with either 1.4 × 106 allogenic canine periodontal ligament-derived cells seeded on de-proteinized bovine bone mineral with 10% collagen (DBBM-C) (test group) or DBBM-C without cells (control group). Specimens were obtained at 3 months, and histological outcomes were studied. RESULTS: The histological analysis showed that total furcation closure occurred very seldom in both groups, being the extent of periodontal regeneration located in the apical third of the defect. The calculated amount of periodontal regeneration at the furcation area was comparable in both the test and control groups (1.93 ± 1.14 mm (17%) versus 2.35 ± 1.74 mm (22%), respectively (p = .37). Similarly, there were no significant differences in the amount of new cementum formation 4.49 ± 1.56 mm (41%) versus 4.97 ± 1.05 mm (47%), respectively (p = .45). CONCLUSIONS: This experimental study was unable to demonstrate the added value of allogenic cell therapy in supra-crestal periodontal regeneration.

Comparison of periodontal ligament and gingiva-derived mesenchymal stem cells for regenerative therapies.

OBJECTIVES: Tissue-engineering therapies using undifferentiated mesenchymal cells (MSCs) from intra-oral origin have been tested in experimental animals. This experimental study compared the characteristics of undifferentiated mesenchymal stem cells from either periodontal ligament or gingival origin, aiming to establish the basis for the future use of these cells on regenerative therapies. MATERIALS AND METHODS: Gingiva-derived mesenchymal stem cells (GMSCs) were obtained from de-epithelialized gingival biopsies, enzymatically digested and expanded in conditions of exponential growth. Their growth characteristics, phenotype, and differentiation ability were compared with those of periodontal ligament-derived mesenchymal stem cells (PDLMSCs). RESULTS: Both periodontal ligament- and gingiva-derived cells displayed a MSC-like phenotype and were able to differentiate into osteoblasts, chondroblasts, and adipocytes. These cells were genetically stable following in vitro expansion and did not generate tumors when implanted in immunocompromised mice. Furthermore, under suboptimal growth conditions, GMSCs proliferated with higher rates than PDLMSCs. CONCLUSIONS: Stem cells derived from gingival biopsies represent bona fide MSCs and have demonstrated genetic stability and lack of tumorigenicity. CLINICAL RELEVANCE: Gingiva-derived MSCs may represent an accessible source of messenchymal stem cells to be used in future periodontal regenerative therapies.

Distinct human T-lymphocyte responses triggered by Porphyromonas gingivalis capsular serotypes.

AIM: Porphyromonas gingivalis can synthesize an extracellular capsule and different serotypes have been described based on capsular antigenicity. On dendritic cells (DCs), the type of capsule present plays a role on the strength of the developed immune response. This study aimed to investigate the T-lymphocyte responses when stimulated with autologous mature DCs exposed to different P. gingivalis K-serotypes. MATERIALS AND METHODS: Naïve CD4(+) T-lymphocytes were obtained from healthy subjects and stimulated with autologous DCs primed with increasing multiplicity of infections of the different P. gingivalis K-serotypes. The Th1, Th2, Th17 and T-regulatory cytokines and transcription factor levels were quantified. RESULTS: Distinct types of response were detected when T-lymphocytes were stimulated by DCs primed with the different P. gingivalis K-serotypes. T-lymphocytes stimulated by K1 or K2-primed DCs elicited higher levels of Th1 and Th17-associated cytokines, T-bet and RORC2 than T-lymphocytes stimulated with DCs primed with the other serotypes. Conversely, the serotypes K3-K5 induced higher levels of Th2-associated cytokines and GATA-3 than the others. CONCLUSIONS: These results demonstrate that DCs primed with the different P. gingivalis K-serotypes elicited distinct T-cell responses. Strains K1 (W83) and K2 (HG184) induced a Th1/Th17 pattern of immune response and K3 (A7A1-28), K4 (ATCC(®49417™) ), and K5 (HG1690) a Th2 response.

Activation of RANKL-induced osteoclasts and memory T lymphocytes by Porphyromonas gingivalis is serotype dependant.

AIM: Destructive periodontitis is associated with a Th1-Th17 immune response and activation of RANKL-induced osteoclasts. In addition, Porphyromonas gingivalis K1 and K2 serotypes induce a strong Th1-Th17 response. This study aimed to investigate whether these P. gingivalis serotypes induce higher osteoclasts activation, by increased Th17-associated RANKL production, and an antigen-specific memory T-lymphocyte response. MATERIAL AND METHODS: The RANKL production and TRAP(+) osteoclast induction were quantified on naïve T lymphocytes stimulated with dendritic cells primed with the P. gingivalis serotypes. The T-bet, GATA-3, RORC2 and Foxp3 expression was correlated with RANKL production. The frequency of proliferating memory T lymphocytes in response to P. gingivalis serotypes was determined in both periodontitis and healthy subjects. RESULTS: T lymphocytes stimulated by K1 or K2-primed dendritic cells elicited higher levels of RANKL and TRAP(+) osteoclasts than cells stimulated with the other serotypes. RANKL positively correlated with RORC2. Whereas periodontitis patients had a higher frequency of memory T lymphocytes responding to K1 or K2, healthy subjects had a higher frequency of memory T lymphocytes responding to K4 or K(-) . CONCLUSIONS: P. gingivalis serotypes K1 and K2, but not others, are associated with an increased production of the osteoclastogenesis-related factor RANKL. This important information suggests that these serotypes could elicit a greater bone resorption in vivo and have a role in the periodontitis pathogenesis.

Differential cytokine expression by human dendritic cells in response to different Porphyromonas gingivalis capsular serotypes.

AIM: Capsular polysaccharides play an important role in the virulence of Gram-positive and Gram-negative bacteria. In Porphyromonas gingivalis, six serotypes have been described based on capsular antigenicity and its pathogenicity has been correlated both in vitro and in animal models. This study aimed to investigate the differential response of human dendritic cells (DCs) when stimulated with different P. gingivalis capsular serotypes. MATERIALS AND METHODS: Using different multiplicity of infection (MOI) of the encapsulated strains K1-K6 and the non-encapsulated K(-) strain of P. gingivalis, the mRNA expression levels for interleukin (IL)-1beta, IL-2, IL-5, IL-6, IL-10, IL-12, IL-13, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, and TNF-beta in stimulated DCs were quantified by real-time reverse transcription-polymerase chain reaction. RESULTS: All P. gingivalis capsular serotypes induced a T-helper type 1 (Th1) pattern of cytokine expression. K1- and K2-stimulated DCs expressed higher levels of IL-1beta, IL-6, IL-12p35, IL-12p40, and IFN-gamma and at lower MOI than DCs stimulated with the other strains. CONCLUSIONS: These results demonstrate a differential potential of P. gingivalis capsular serotypes to induce DC responses and a higher capacity of strains K1 W83 and K2 HG184 than other K serotypes to trigger cytokine expression.