The application of immune regenerative strategies to deal with unsolved pathologies, such as tendinopathies, is getting attention in the field of tissue engineering exploiting the innate immunomodulatory potential of stem cells [1]. In this context, Amniotic Epithelial Cells (AECs) represent an innovative immune regenerative strategy due to their teno-inductive and immunomodulatory properties [2], and because of their high paracrine activity, become a potential stem cell source for a cell-free treatment to overcome the limitations of traditional cell-based therapies. Nevertheless, these immunomodulatory mechanisms on AECs are still not fully known to date. In these studies, we explored standardized protocols [3] to better comprehend the different phenotypic behavior between epithelial AECs (eAECs) and mesenchymal AECs (mAECs), and to further produce an enhanced immunomodulatory AECs-derived secretome by exposing cells to different stimuli. Hence, in order to fulfill these aims, eAECs and mAECs at third passage were silenced for CIITA and Nrf2, respectively, to understand the role of these molecules in an inflammatory response. Furthermore, AECs at first passage were seeded under normal or GO-coated coverslips to study the effect of GO on AECs, and further exposed to LPS and/or IL17 priming to increase the anti-inflammatory paracrine activity. The obtained results demonstrated how CIITA and Nrf2 control the immune response of eAECs and mAECs, respectively, under standard or immune-activated conditions (LPS priming). Additionally, GO exposition led to a faster activation of the Epithelial-Mesenchymal transition (EMT) through the TGFβ/SMAD signaling pathway with a change in the anti-inflammatory properties. Finally, the combinatory inflammatory stimuli of LPS+IL17 enhanced the paracrine activity and immunomodulatory properties of AECs. Therefore, AECs-derived secretome has emerged as a potential treatment option for inflammatory disorders such as tendinopathies.

Acknowledgement: This research is part of the P4FIT project ESR1, funded under the H2020-ITN-EJD-Marie-Skłodowska-Curie grant agreement 955685.

Adipose-derived stem cells (ADSCs) are an effective alternative for Teno-regeneration. Despite their applications in tendon engineering, the mechanisms promoting tendon healing still need to be understood. Since there is scattered information on ovine ADSCs, this research aims to investigate in vitro their teno-differentiation for potential use in preclinical tendon regeneration models.

Ovine ADSCs were isolated from the tail region according to FAT-STEM laboratories, expanded until passage six (P6), and characterized in terms of stemness, adhesion and MHC markers by Flow Cytometry (FCM) and immunocytochemistry (ICC). Cell proliferation and senescence were evaluated with MTT and Beta-galactosidase assays, respectively. P1 ADSCs’ teno-differentiation was assessed by culturing them with teno-inductive Conditioned Media (CM) or engineering them on tendon-mimetic PLGA scaffolds. ADSCs teno-differentiation was evaluated by morphological, molecular (qRT-PCR), and biochemical (WesternBlot) approaches.

ADSCs exhibited mesenchymal phenotype, positive for stemness (SOX2, NANOG, OCT4), adhesion (CD29, CD44, CD90, CD166) and MHC-I markers, while negative for hematopoietic (CD31, CD45) and MHC-II markers, showing no difference between passages. ICC staining confirmed these results, where ADSCs showed nuclear positivity for SOX2 (≅ 56%) and NANOG (≅ 67%), with high proliferation capacity without senescence until P6. Interestingly, ADSCs cultured with the teno-inductive CM did not express tenomodulin (TNMD) protein or gene. Conversely, ADSCs seeded on scaffolds teno-differentiated, acquiring a spindle shape supported by TNMD protein expression at 48h (p<0.05 vs. ADSCs 48h) with a significant increase at 14 days of culture (p<0.05 vs. ADSCs + fleece 48h).

Ovine ADSCs respond differently upon distinct teno-inductive strategies. While the molecules on the CM could not trigger a teno-differentiation in the cells, the scaffold's topological stimulus did, resulting in the best strategy to apply. More insights are requested to better understand ovine ADSCs’ tenogenic commitment before using them in vivo for tendon regeneration.

Acknowledgements: This research is part of the P4FIT project ESR5, under the H2020MSCA-ITN-EJD-P4 FIT-Grant Agreement ID:955685.

Background: Control of acute postoperative pain remains a serious problem. Postoperative pain is associated with an increase in thrombotic or respiratory complications. In the other hand the association between surgery, acute postoperative pain and ongoing chronic pain is well defined.

Target: To evaluate the incidence of severe pain after surgery for degenerative lumbar pain, with two analgesic techniques; intravenous analgesia (i.v.) (group 1) and patient controlled analgesia (PCA) (group 2).

Study design: Retrospective study with dates obtains prospectively.

Patient sample: We studied 206 patients operated between january 04 and june 05. Group 1 (intravenous) 80 patients and 126 in group 2 (PCA).

Outcomes mesasures: Percentage of patients with severe pain, number of rescues and complications.

Materials and methods: The type of postoperative analgesia administrated was decided by the anaesthesiologist. To measure pain intensity the VAS was assessed every 6 hours and worst score was used, excluding recovery room. Type of rescue analgesia was the same in all patients and these was recommended in VAS > 3. We evaluate sex, age and comorbidity by ASA. We have defining analgesic ‘failure’ by the overall incidence of pain intensity in two categories: the percentage of patients who experienced moderate-severe pain (VAS > 3) and severe pain (VAS> or = 7). As the pain scores were not normally distributed we not used mean and SD of VAS. The number of rescues and complications were also evaluated.

Results: There was not differences in median age (group 1 50’85 sd 15’4; group 2 52’44 sd 15’4 p=0’47), ASA (group 1 1’89 sd 0’75; group 2 1’90 sd 0’57 p=0’88) or diagnosis between two groups. There were differences in percentages of sexes, group 1 with 40% of women and 62’69% in group 2 (p=0’013). There were not differences in incidence of patients with moderate-severe pain (group 1 15/80; group 2 30/126. p=0’392) neither in incidence of patients with severe pain (group 1 33/80; group 2 51/126. p=0’912). There were not differences in number of rescues (p=0’912) neither in number of complications between groups. Global incidence of VAS > 3 were 40’8 but the incidence of rescues were 25’2%

Conclusions: Our findings suggest that both techniques have similar effectiveness, although the global incidence of severe pain was not optimal (21’8%). It is important to remark the different between incidence of patients with VAS > 3 and number of rescues administrated.