Merkel cells and permanent disesthesia in the oral mucosa after soft tissue grafts

Abstract

Connective tissue grafts are routinely procedures in the treatment of gingival defects. The clinical success of the gingival tissue graft procedures anyway should ensure not only the aesthetic integration between the tissues but also the physiological activity of the graft in terms of sensitivity and immunity because the skin and the mucosae constitute the first natural aspecific borders against pathogens. The aim of this paper was to investigate nervous net recovery after connective graft procedure, in relation with sensorial alteration in the injured area. Results showed that there is a close link among the number of Merkel cells and the alteration of sensations. Merkel cells can be found isolated standing in the basal layer, supposed to have neuroendocrine functions in the epithelia or in larger group not associated with nerves; when found in association with nerves they are named Merkel complexes, acting as slow adapter mechanical receptor. Our data can be explained in two ways: Merkel cells increase as a consequence of tissue injury, a sort of "SOS cells" that secrete neuroendocrine signals to guide tissue healing; as an alternative the presence of the Merkel cells could be read as a derailment of tissue regeneration with the stop of cellular differentiation in the direction of an abnormal proliferation, a sort of mad stem cell.

Unexpected resilience to experimental gingivitis of subepithelial connective tissue grafts in gingival recession defects: a clinical–molecular evaluation

“…At the end of experiment, the GI and AngBS appeared statistically higher in control sites. This clinical evidence, taken together with histological and immunohistochemical data that show loss of vasomotor control due to a decrease in nerve fibers in grafted tissues , suggest that an attenuated clinical inflammatory response in grafts may be due to an alteration of the mechanisms of “neurogenic inflammation” . The results can be linked to our previous data where alteration of sensation in tissue grafts was associated with an increased amount of free Merkel cells.…”

“…The results can be linked to our previous data where alteration of sensation in tissue grafts was associated with an increased amount of free Merkel cells. Specifically, Merkel cells were absent in normal gingival samples but were present in the palatal donor sites, together with a reduction in nerva vasorum ; these data came together with sensorial alteration of the patient when the grafted mucosa was challenged. We believe that these findings can be related to the differences in terms of gingival crevicular fluid and IL‐1β observed in the present study.…”

“…Successful connective tissue graft procedures should ensure not only an esthetic integration between tissues but also a physiological activity of the graft in terms of sensitivity and immunity . We have shown previously that alteration of the epicritical and/or protopatical sensation was found in all the gingival sites where SCTG was performed 12 mo before the sensorial tests, which was possibly related to an increase of free Merkel cells in the grafts . Similarly, an altered inflammatory response of the grafted tissues could affect the success of SCTGs.…”

Osteogenic Potential of Human Oral‐Periosteal Cells (PCs) Isolated From Different Oral Origin: An In Vitro Study

“…All the clones obtained from different patients showed a marked expression of CD73, CD90, CD105, and CD29 with a concomitant absence of hematopoietic markers CD45 and CD34 (Dominici et al, ). Interestingly, oral‐PCs demonstrated a minimum presence of CD117 surface marker (2.2% average positivity), indicating that these cells have a probable origin from Schneider membrane in maxillary sinus cavity (Aimetti et al, ; Graziano et al, ). Since we demonstrated their mesenchymal features, we evaluated the “stemness” and the proliferative potency of all cell clones collected.…”

Origin and Regenerative Potential of Vertebrate Mechanoreceptor-Associated Stem Cells

“…In an intriguing initial study, reinnervation and an increase of the Merkel cell number after experimental nerve crush were observed 40–100 days after the surgery [7, 43]. Importantly, the authors were able to show that the newly formed Merkel cells appeared physiologically normal and demonstrated typical histological features via electron microscopy and toluidine blue staining.…”