The objective is to detect any possible correlation between the modified Rodnan skin score (mRSS) and dermal thickness (DT) measured by skin high-frequency ultrasound (US) and the percentage of circulating fibrocytes in patients with limited cutaneous systemic sclerosis (lcSSc). Eight lcSSc patients and five healthy subjects (control group, CNT) were enrolled. The skin involvement was evaluated by mRSS and US (18 and 22 MHz probes) in all 13 subjects in the 17 standard skin areas evaluated by mRss. Circulating fibrocytes were isolated from the peripheral blood mononuclear cells (PBMCs) of all lcSSc patients and the CNT group to analyze their percentage at baseline time (T0) when the experiments started with PBMCs\' isolation and collection and after 8 days of culture (T8). Non-parametric tests were used for the statistical analysis. A positive correlation between the percentage of circulating fibrocytes at T0, mRSS (p = 0.04 r = 0.96), and DT-US, evaluated by the 22 MHz and the 18 MHz probes (p = 0.03, r = 0.66 and p = 0.05, r = 0.52, respectively), was observed in lcSSc patients. Conversely, at T8, there was no correlation (p > 0.05) between these parameters in lcSSc group. In the CNT group, no correlations between mRSS or DT-US and the percentage of circulating fibrocytes were observed both at T0 and T8. The study shows the presence of a significant relationship between the percentage of circulating fibrocytes and DT, as evidenced by both mRSS and US, in limited cutaneus SSc. This observation may well suggest the reasonable hypothesis of a crucial contribution of circulating fibrocytes to skin fibrosis progression, which might be considered as further biomarkers.

In extensive burns it becomes difficult for fibroblasts to migrate from the periphery of the healthy tissue and colonize the injured area. Even under such circumstances healing takes place, and this is attributed to the differentiation of circulating fibrocytes which enter the wound site. This normal cell type is identified in keloid fibroblasts: it expresses fibrocyte markers and secretes extra cellular matrix proteins. In-vitro collagen contraction assay reveals that fibrocytes contract collagen gels with an efficacy similar to normal fibroblasts. The contribution of fibrocytes to the formation of keloid fibroblasts in post-burn healing is discussed.
Quand le patient est atteint de brûlures de grande extension, pour les fibroblastes il devient difficile de migrer de la périphérie du tissu sain pour coloniser la zone lésée. Même dans ces conditions la guérison a lieu, ce qui est attribué à la différenciation des fibrocytes en circulation qui entrent dans la plaie. Ce type normal de cellule a été identifié dans les fibroblastes chéloïdaux: il exprime des marqueurs des fibrocytes et sécrète des protéines de la matrice extracellulaire. Les épreuves in vitro sur la contraction du collagène révèlent que les fibrocytes contractent le gel de collagène avec une efficacité similaire à celle des fibroblastes normaux. Les Auteurs concluent avec une discussion sur la contribution des fibrocytes à la formation des fibroblastes chéloïdaux dans la phase finale de la guérison des brûlures.