Gingival fibroblasts inhibit MMP-1 and MMP-3 activities in an ex-vivo artery model

Hiding in Plain Sight: Human Gingival Fibroblasts as an Essential, Yet Overlooked, Tool in Regenerative Medicine

Adult human gingival fibroblasts (HGFs), the most abundant cells in the oral cavity, are essential for maintaining oral homeostasis. Compared with other tissues, adult oral mucosal wounds heal regeneratively, without scarring. Relative to fibroblasts from other locations, HGFs are relatively refractory to myofibroblast differentiation, immunomodulatory, highly regenerative, readily obtained via minimally invasive procedures, easily and rapidly expanded in vitro, and highly responsive to growth factors and cytokines. Consequently, HGFs might be a superior, yet perhaps underappreciated, source of adult mesenchymal progenitor cells to use in tissue engineering and regeneration applications, including the treatment of fibrotic auto-immune connective tissue diseases such as scleroderma. Herein, we highlight in vitro and translational studies that have investigated the regenerative and differentiation potential of HGFs, with the objective of outlining current limitations and inspiring future research that could facilitate translating the regenerative potential of HGFs into the clinic.

An ex vivo study of photobiostimulation in the treatment of skin pathologies

Photodynamic therapy (PDT) and low level laser therapy (LLLT) may mutually improve the outcomes on the healing process of chronic wounds and other skin pathologies, through processes known to stimulate the proliferation of dermal cellular structures, as well as antimicrobial application. This study proposes the use of nanoemulsion containing aluminium phthalocyanine chloride (ClAlPc) as photosensitizer (PS), to establish the most appropriate protocol for photostimulation in human skin biopsies, associated to type I collagen and elastin production. The combined effect of PS and light (diode laser at 670 nm) at three different doses is compared to the effect of light itself at doses of 70, 140 and 700 mJ ċ cm^-2 , 7 and 14 days after irradiation. Histological analysis reveals the increase in collagen and elastin, higher than 20%, 14 days after treatment with PS and light at 140 mJ ċ cm^-2 . Higher doses of light promote an inhibitory effect, leading to tissue degradation. In addition, the expression levels of the enzymes MMP-2 and MMP-9 (Gelatinases A and B - participant in various processes including tumoral progression and wound healing) are detected by gelatin zymography, reinforcing the efficacy of the combined treatment with PS and light at the intermediate dose.

The differentiation potential of gingival mesenchymal stem cells induced by apical tooth germ cell‑conditioned medium

Gingival-derived mesenchymal stem cells (GMSCs) have recently been harvested; however, the use of GMSCs in periodontal tissue engineering requires further study. The present study established an indirect co‑culture system between rat apical tooth germ‑conditioned medium (APTG‑CM) and GMSCs, in order to determine the effects on periodontal tissue differentiation in vitro and in vivo. Using the limiting dilution technique, single‑colony derived human GMSCs and periodontal ligament stem cells (PDLSCs) were isolated and expanded to obtain homogeneous populations. PDLSCs were used as a positive control group. Cell cycle distribution, alkaline phosphatase (ALP) activity, mineralization behavior, expression of genes associated with a cementoblast phenotype (osteocalcin, bone sialoprotein, ALP, type I collagen, cementum‑derived protein 23), and in vivo differentiation capacities of GMSCs/PDLSCs co‑cultured with APTG‑CM were evaluated. Flow cytometry indicated that GMSCs and PDLSCs were positive for STRO‑1 and CD105, whereas CD45 expression was negative. The cell types were capable of forming colonies, and of osteogenic and adipogenic differentiation in response to appropriate stimuli. The induced GMSCs and PDLSCs exhibited numerous characteristics associated with cementoblast lineages, as indicated by increased proliferation and ALP activity, and upregulated expression of cementum‑associated genes in vitro. In vivo, cementum/periodontal ligament‑like structures were shown to form along the dentin surface and ceramic bovine bone in GMSCs and PDLSCs induced by APTG‑CM group. Conversely, vertical fibers could not insert in the control group, which was not co‑cultured with APTG‑CM. In conclusion, GMSCs are likely to have a role in periodontal tissue regeneration. In addition, APTG‑CM was able to provide a cementogenic microenvironment and promote differentiation of GMSCs along the cementoblastic lineage.

Comparative study of abdominal and thoracic aortic aneurysms: their pathogenesis and a gingival fibroblasts-based ex vivo treatment

Aortic aneurysms (AAs) consist of slow proteolysis and loss of both collagen and elastin matrix in the aorta wall, leading to wall dilation, weakening and rupture in well-advanced lesions. This can occur in both abdominal aorta (Abdominal Aortic Aneurysm: AAA) and thoracic aorta (Thoracic Aortic Aneurysm: TAA). To date, no non-surgical therapy has been proposed to slow or stop AA progression. Previously published preclinical studies from our team using an aneurysm rabbit model showed a promising concept for treatment of AAs with gingival fibroblast (GFs) which are readily available cells. In this study, we investigated the possible tissue repair of human AAAs and TAAs using ex vivo models co-cultured with GFs. Histological analysis showed that TAA and AAA are two distinct pathologies. Both lesions presented destruction of the aorta wall, highly evidenced in AAA samples. The results have confirmed the presence of the bacterial Porphyromonas gingivalis (Pg) protein in all AAA samples, but not in TAA samples, indicating the possible role of an infectious factor in the developing and progression of AAA lesions compared to TAA. The co-culture of GFs with AA lesions shows increased expression of TIMP-1, the inhibitor of the aneurysm severity marker MMP-9. Our study indicates that GFs might ameliorate aorta wall reestablishment in both AA types by their regenerative and immunomodulatory capacities. It also demonstrates the possible infectious cause of AAA compared with TAA that may explain their different behavior.

Collagenolytic activity is suppressed in organ-cultured human skin exposed to a gadolinium-based MRI contrast agent

OBJECTIVE

Human skin produces increased amounts of matrix metalloproteinase-1 (MMP-1) when exposed in organ culture to Omniscan, one of the gadolinium-based MRI contrast agents (GBCA). MMP-1, by virtue of its ability to degrade structural collagen, contributes to collagen turnover in the skin. The objective of the present study was to determine whether collagenolytic activity was concomitantly up-regulated with increased enzyme.

MATERIALS AND METHODS

Skin biopsies from normal volunteers were exposed in organ culture to Omniscan. Organ culture fluids obtained from control and treated skin were examined for ability to degrade type I collagen. The same culture fluids were examined for levels of MMP-1, tissue inhibitor of metalloproteinases-1 (TIMP-1), and complexes of MMP-1 and TIMP-1.

RESULTS

Although MMP-1 was increased in culture fluid from Omniscan-treated skin, there was no increase in collagenolytic activity. In fact, collagenolytic activity declined. Increased production of TIMP-1 was also observed in Omniscan-treated skin, and the absolute amount of TIMP-1 was greater than the amount of MMP-1. Virtually all of the MMP-1 was present in MMP-1-TIMP-1 complexes, but the majority of TIMP-1 was not associated with MMP-1. When human dermal fibroblasts were exposed to TIMP-1 (up to 250 ng/mL), no increase in proliferation was observed, but an increase in collagen deposition into the cell layer was seen.

CONCLUSION

Gadolinium-based MRI contrast agent exposure has recently been linked to a fibrotic skin condition in patients with impaired kidney function. The mechanism is unknown. The increase in TIMP-1 production and concomitant reduction in collagenolytic activity demonstrated here could result in decreased collagen turnover and increased deposition of collagen in lesional skin.

Gingival fibroblast inhibits MMP-7: evaluation in an ex vivo aorta model

Matrix metalloproteinases (MMP) play a deleterious role in numerous vascular diseases. In contrast, gingival matrix remodelling is adequately regulated by the gingival fibroblast (GF). Here, we aimed to evaluate the GF activity on MMP-7 expression and secretion in coculture with aorta rings. We evaluated MMP-7 transcription and secretion in rabbit aorta rings cultured or not with gingival fibroblasts in collagen gels. GF induced an increase of TIMP-1 transcription and secretion, followed, similarly to other MMPs, by the formation of TIMP-1/MMP-7 complexes. There was also a decrease of MMP-7 mRNA by RT-PCR in aorta rings cocultured with gingival fibroblasts. Interestingly, in contrast with other MMPs (which were not influenced at a transcription level), GF stimulated the release of TGF-beta1, which in turn inhibited the transcription and synthesis of MMP-7, as shown by neutralizing MMP-7 inhibition due to gingival fibroblast by overexpressing decorin (a TGF beta 1 inhibitor) or by silencing TGF beta 1 using siRNA. We showed that healing properties of the GF could be transposed to another organ, i.e., ex vivo aneurism model, implicating a down-regulation of MMP-7.

In situ zymography and immunolabeling in fixed and decalcified craniofacial tissues

In situ zymography is a very important technique that shows the proteolytic activity in sections and allows researchers to observe the specific sites of proteolysis in tissues or cells. It is normally performed in non-fixed frozen sections and is not routinely performed in calcified tissues. In this study, we describe a technique that maintains proteolytic activity in fixed and decalcified sections obtained after routine paraffin sectioning in conventional microtome and cryostat sections. We used adult rat hemimandibles, which presented bone, enamel, and dentine matrices; the substrate used was dye-quenched-gelatin. Gelatinolytic activity was colocalized with MMP-2 using fluorescent antibodies. Specific proteolytic activity was observed in all sections, compatible with metalloproteinase activity, particularly in dentine and bone. Furthermore, matrix metalloproteinase-2 was colocalized to the sites of green fluorescence in dentine. In conclusion, the technique presented here will allow in situ zymography reactions in fixed, decalcified, and paraffin-embedded tissues, and we showed that paraformaldehyde-lysine-periodate-fixed cryostat sections are suitable for colocalization of gelatinolytic activity and protein labeling with antibodies.