ABSTRACT Background Predicting outcome in horses presenting with colic remains challenging. Objectives To test whether arterial blood samples in horses admitted for colic predict outcome to hospital discharge for different colic types. Methods Arterial blood samples collected on admission from 358 horses undergoing medical or surgical management of colic were evaluated for pH, PaO2, PaCO2, Na+, K+, iCa2+, Cl−, HCO3− (P), HCO3− (P, set), Base (B), Base (ecf) and anion gap. Categories were small intestinal non‐strangulating (SINS) or strangulating (SIS) lesions, large colon non‐volvulus (LCNV) or volvulus (LCV), small colon non‐strangulating (SCNS) or strangulating (SCS) lesions, viscus rupture or other. Multivariable logistic regression models were developed based on survival, or not, to hospital discharge. Odd ratios (ORs) with 95% confidence intervals (95%CI) and area under the curve receiver operator characteristics (AUROC), sensitivity, specificity and positive and negative predictive values were calculated at a cut‐off value of p = 0.5. Results A total of 295/358 (82.4%) horses survived to hospital discharge. Variables retained as significantly associated with survival were PaO2 for SINS (OR 1.15, 95%CI 1.04–1.27), PaO2 (OR 1.06, 95% CI 1.01–1.11) and Na+ (OR 1.24, 95% CI 1.02–1.52) for SIS, Ca2+ (OR 175.1, 95% CI 2.20–13958) and HCO3− (P) (OR 1.18, 95% CI 1.01–1.37) for LCNV and PaCO2 (OR 1.47, 95% CI 1.05–2.06) for LCV. AUROCs showed acceptable‐excellent discrimination (range: 0.7–0.9), excellent sensitivity (range: 91%–100%) but poor–fair specificity (range: 8%–50%). Conclusions Arterial blood is good at predicting survival based on colic type but less accurate at predicting those horses which do not survive to hospital discharge.

BackgroundTrimming is critical for a functioning equine hoof. Pressure distribution provides information on loading; however, information on the effects of trimming on pressure distribution is lacking.ObjectivesTo describe the pressure changes of equine fore feet following trimming.Study designCross-sectional cohort study.MethodsFifty sound horses were recruited. Eighteen external hoof measures of the dorsal, lateral, medial and solar aspects were obtained before and after trimming from 94 fore feet. Horses were walked over a pressure mat before and after trimming and pressure maps of the solar surface created. Percentage change in hoof measures were assessed. Factors associated with an increase in pressure in the frog region after trimming were entered into a forward likelihood ratio logistic regression model. Odd ratios (ORs) with 95% confidence intervals (CI) and area under the curve receiver operator characteristics (AUROC) were calculated. Sensitivity and specificity were calculated at a cut-off value of p = 0.5.ResultsTrimming resulted in a significant increase in pressure, topographically mapped to the frog region, in 12/94 (13% 95% CI 6; 20) feet. Percentage difference in bearing border length (OR 0.66 95% CI 0.51; 0.86), heel buttress to centre of pressure distance (OR 1.30 95% CI 1.10; 1.53), heel angle (lateral side) (OR 1.11 95% CI 1.04; 1.19) and heel length (medial side) (OR 0.92 95% CI 0.85; 0.99) were retained in the final model associated with increased pressure in the frog region following trimming. AUROC was excellent (0.94 95% CI 0.88; 0.99) with fair sensitivity (58% [95% CI 50; 66]) and excellent specificity (98% [95% CI 78; 118]).Main limitationsSubjective lameness exam; horse velocity unmeasured.ConclusionsMeasuring pressure changes over the solar surface of the equine fore foot after trimming identified that an increased pressure in the frog region was linked to specific changes in hoof shape.

BackgroundWound infusion catheters (WICs) have been used in humans and some veterinary species for post-operative local anesthetic administration following a variety of surgical procedures, aiming to reduce post-operative analgesia requirements and improve patient comfort. Benefit in reduction in pain, post-operative analgesia requirements and length of hospital stay are well documented in humans, but use of WICs may not have been widely adopted in veterinary species due to the concern of increased complications, such as dehiscence or surgical site infection (SSI), creating a barrier to their use. This study aimed to evaluate the use of WICs in horses undergoing standing partial ostectomy surgeries, document complications and investigate if the incidence of SSI was equivalent between those horses that did and did not have a WIC.MethodsClinical records were searched between January 2010–December 2023 for horses undergoing standing partial ostectomy surgery of thoracolumbar vertebral spinous processes at one institution. Population variables (age, breed, bodyweight), placement of a WIC or not, post-operative complications, analgesia protocols and surgical time were recorded. Horses received up to 0.1 mg kg−1 bupivacaine (0.5 mg mL−1) every 6–8 h via the WIC where one was placed. To compare SSI complication incidence between using or not using a WIC, a proportional independent equivalence test was used.ResultsThere were 64 horses included in the final analysis with a WIC placed in 29/64 horses (45.3%) and 35/64 (54.7%) having no WIC placed at surgery. Incidence of short-term SSI was 11.4% (no WIC used) and 13.8% (WIC used), respectively. The difference in proportion of SSI between the presence or absence of a WIC was not significant [−0.024 (90% CI −0.181; 0.133); p = 0.94].ConclusionThe incidence of SSIs was equivalent between groups whether a WIC was used or not. WICs should be considered as part of a multi-modal analgesic approach in the post-operative period. Further research into local anesthetic dosing and its impact on rescue analgesia requirements and pain-scores is warranted.

Purpose (the aim of the study): This study addresses the critical question of the involvement of the cell surface endocytic receptor, the low-density lipoprotein receptor-related protein 1 (LRP1) in osteoarthritis (OA) in vivo. Our previous studies using cartilage explants from human patients have shown that LRP1 plays a vital role in maintaining healthy cartilage by removing various biologically active molecules from the tissue and degrading them in the cell. However, in OA cartilage, the function of the LRP1 receptor is largely lost due to increased proteolytic shedding of LRP1 ectodomain. Inhibition of proteolytic enzymes responsible for LRP1 shedding restores endocytic capacity of the cells and protect cartilage degradation ex vivo, but the role of LRP1 in OA development in vivo remains incompletely understood.

Strangulating small intestinal disease (SSID) in horses carries a poor prognosis for survival, especially following resection of ischaemic tissue. The margins of a resection are principally based on visual appraisal of the intestine during surgery. We hypothesized that histological evaluation of resected tissue may identify occult changes indicative of prognosis. Small intestinal samples from 18 horses undergoing resection for SSID and 9 horses euthanised for reasons unrelated to gastrointestinal pathology were utilised. Histological appearance was used to generate a ‘total damage score’ (TDS) for the control tissue, grossly normal tissue at oral and aboral extremities (sections OR1 and AB1) of the resected intestine, and oral and aboral extremities of visually abnormal tissue (sections OR2 and AB2) from SSID horses. The relationship between TDS and long-term post-operative survival was investigated. TDS was not different between control tissues and OR1 and AB1 sections. Five surgical cases were alive at follow-up, the longest follow-up time being 2561 days. Based on the median scores for SSID cases versus controls, cut-off values were generated to evaluate post-operative survival versus TDS. Only OR2 TDS was significantly associated with survival, with a higher (worse) score indicating longer survival. More severe tissue insult may expedite rapid progression to surgery, improving post-operative outcomes.

The study aimed to investigate if arterial blood analysis in conscious horses presenting with signs of colic and breathing ambient air had diagnostic or prognostic value. Arterial blood samples from 352 horses presenting with colic at a university equine referral hospital were analysed for pH, partial pressure of carbon dioxide (PaCO2), partial pressure of oxygen (PaO2), concentrations of sodium (Na+), potassium (K+), ionised calcium (Ca2+) and chloride (Cl-), actual and standardised plasma bicarbonate concentration (HCO3- (P) and HCO3- (P, st)), blood and extracellular fluid base excess (Base (B) and Base (ecf)) and anion gap (AG). Results were compared to previously reported values for healthy horses, and comparisons were made between final diagnosis, treatment and survival to hospital discharge. Significant differences were found between colic cases and healthy reference values between some primary aetiologies. Overall, surgical and non-surgical colic cases differed in Ca2+ and Cl- concentrations and Ca2+ differed between cases that survived to discharge and those that did not. PaO2 differed between small intestinal surgical cases that survived and those that did not. From these results, we developed regression models that demonstrated excellent or good predictive value in identifying the likelihood of surgical versus medical management and survival to hospital discharge.

SummaryAn 8‐year‐old Warmblood‐cross mare presented for investigation of acute onset left hindlimb lameness. Nuclear scintigraphy identified a marked, focal, increase in radiopharmaceutical uptake in the distal aspect of the left tibia. Radiography revealed a large, oval, multi‐loculated radiolucent area within the medulla of the distal metaphysis of the left tibia. The mare was treated conservatively for 6 months but showed little improvement in the lameness so the owner elected for euthanasia. Post‐mortem computed tomographic imaging revealed a large, oval, hypoattenuating area within the distal tibia, surrounded by a thick, irregular, sclerotic border. The lesion occupied the majority of the medullary cavity but the cortical bone was unaffected. Gross and histopathological examination confirmed a diagnosis of a bone infarction in the medullary cavity of the distal tibia.

OBJECTIVE:This study investigated mice serum and joint microRNA expression profiles in ageing and osteoarthritis to elucidate the role of microRNAs in the development and progression of disease, and provide biomarkers for ageing and osteoarthritis. DESIGN:Whole joints and serum samples were collected from C57BL6/J male mice and subjected to small RNA sequencing. Groups used included; surgically-induced post-traumatic osteoarthritis, (DMM; 24 months-old); sham surgery (24 months-old); old mice (18 months-old); and young mice (8 months-old). Differentially expressed microRNAs between the four groups were identified and validated using real-time quantitative PCR. MicroRNA differential expression data was used for target prediction and pathway analysis. RESULTS:In joint tissues, miR-140-5p, miR-205-5p, miR-682, miR-208b-3p, miR-499-5p, miR-455-3p and miR-6238 were differentially expressed between young and old groups; miR-146a-5p, miR-3474, miR-615-3p and miR-151-5p were differentially expressed between DMM and Sham groups; and miR-652-3p, miR-23b-3p, miR-708-5p, miR-5099, miR-23a-3p, miR-214-3p, miR-6238 and miR-148-3p between the old and DMM groups. The number of differentially expressed microRNAs in serum was higher, some in common with joint tissues including miR-140-5p and miR-455-3p between young and old groups; and miR-23b-3p, miR-5099 and miR-6238 between old and DMM groups.We confirmed miR-140-5p, miR-499-5p and miR-455-3p expression to be decreased in old mouse joints compared to young, suggesting their potential use as biomarkers of joint ageing in mice. CONCLUSIONS:MiR-140-5p, miR-499-5p and miR-455-3p could be used as joint ageing biomarkers in mice. Further research into these specific molecules in human tissues is now warranted to check their potential suitability as human biomarkers of ageing.

BACKGROUND Neurovascular variation may be relevant when performing surgical techniques to the proximal plantar metatarsal region. OBJECTIVES To document variations in the neurovascular anatomy of the proximal plantar metatarsal region and study the relationship of the neurovascular components to each other and other structures located in this area. STUDY DESIGN Descriptive anatomical study. METHODS Paired cadaver hind limbs from 15 horses were dissected from the distal tibia to the metatarsophalangeal joint. Deep branch of the lateral plantar nerve (DBLPN) length, location of its origin from the lateral plantar nerve (LPN), individual DBLPN ramifications into the suspensory ligament (SL) and relationship of the DBLPN to the plantar arch and accessory ligament of the deep digital flexor tendon (ALDDFT) were recorded. RESULTS Mean DBLPN length was 5.8 ± 1.7 cm with the nerve arising 3.7 ± 1.5 cm proximal to the head of the fourth metatarsal bone (MTIV). There was a median of three individual DBLPN ramifications (range 2-6) entering the SL. There were no significant left/right differences. In 57% (CI 39%-74%; n = 17) limbs, the deep plantar arch was superficial to the DBLPN, whereas in 33% (CI 16%-50%; n = 10) limbs, the DBLPN passed between the venous and arterial components of the arch. In 10% (CI 1%-20%; n = 3) limbs, the deep plantar arch was deep to the DBLPN. In 67% (CI 50%-84%; n = 20) limbs, the DBLPN was superficial to the ALDDFT, whereas in 33% (CI 16%-50%; n = 10) limbs, the nerve ran deep to the ALDDFT. An additional branch from the LPN was noted in one limb. MAIN LIMITATIONS Limbs were used from horses with unknown clinical history. CONCLUSIONS Anatomical variation, in particular the relationship of the DBLPN and deep metatarsal fascia to the deep plantar arch and the ALDDFT is an important consideration when undertaking surgical approaches to the proximal plantar metatarsal region.

CCN2 is a matricellular protein involved in several critical biological processes. In particular, CCN2 is involved in cartilage development and in osteoarthritis. CCN2 null mice exhibit a range of skeletal dysmorphisms, highlighting its importance in regulating matrix formation during development, however its role in adult cartilage remains unclear. The aim of this study was to determine the role of CCN2 in postnatal chondrocytes in models of post-traumatic osteoarthritis (PTOA). CCN2 deletion was induced in articular chondrocytes of male transgenic mice at 8 weeks of age. PTOA was induced in knees either surgically or non-invasively by repetitive mechanical loading at 10 weeks of age. Knee joints were harvested, scanned with micro-CT, and processed for histology. Sections were stained with toluidine blue and scored using the OARSI grading system. In the non-invasive model cartilage lesions were present in the lateral femur but no significant differences were observed between wildtype (WT) and CCN2 knockout (KO) mice 6 weeks post-loading. In the surgical model, severe cartilage degeneration was observed in the medial compartments but no significant differences were observed between WT and CCN2 KO mice at 2, 4, and 8 weeks post-surgery. We conclude that CCN2 deletion in chondrocytes did not modify the development of PTOA in mice, suggesting that chondrocyte expression of CCN2 in adults is not a critical player in protecting cartilage from the degeneration associated with PTOA. Summary Statement Post-natal deletion of CCN2 in chondrocytes does not affect the development of post-traumatic osteoarthritis in mice.

OBJECTIVE:This study investigated the effect of hUC-MSCs on osteoarthritis (OA) progression in a xenogeneic model. DESIGN:Male, 10 week-old C57BL/6 mice underwent sham surgery (n = 15) or partial medial meniscectomy (PMM; n = 76). 5x105 hUC-MSCs (from 3 donors: D1, D2 and D3) were phenotyped via RT-qPCR and immunoprofiling their response to inflammatory stimuli.They were injected into the mouse joints 3 and 6 weeks post-surgery, harvesting joints at 8 and 12 weeks post-surgery, respectively. A no cell 'control' group was also used (n = 29). All knee joints were assessed via micro-computed tomography (μCT) and histology and 10 plasma markers were analysed at 12 weeks. RESULTS:PMM resulted in cartilage loss and osteophyte formation resembling human OA at both time-points. Injection of one donor's hUC-MSCs into the joint significantly reduced the loss of joint space at 12 weeks post-operatively compared with the PMM control.This 'effective' population of MSCs up-regulated the genes, IDO and TSG6, when stimulated with inflammatory cytokines, more than those from the other two donors.No evidence of an inflammatory response to the injected cells in any animals, either histologically or with plasma biomarkers, arose. CONCLUSION:Beneficial change in a PMM joint was seen with only one hUC-MSC population, perhaps indicating that cell therapy is not appropriate for severely osteoarthritic joints. However, none of the implanted cells appeared to elicit an inflammatory response at the time-points studied. The variability of UC donors suggests some populations may be more therapeutic than others and donor characterisation is essential in developing allogeneic cell therapies.

BACKGROUND:Opioid epidural analgesia has been shown to provide effective analgesia in horses. There is a lack of evidence regarding the effect of opioid epidural analgesia on quality of recovery in horses. OBJECTIVES:Identify whether opioid epidural analgesia influences quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis. STUDY DESIGN:Single-centre retrospective cross-sectional study. METHODS:Data were obtained from the clinical records of horses which had undergone arthroscopic or tenoscopic surgery for management of hindlimb synovial sepsis over a 9-year period in a referral hospital population. Multivariable logistic regression analysis was used to identify the perioperative factors that impact on quality of recovery. RESULTS:Records from 149 horses, undergoing 170 general anaesthetics were included. Multivariable logistic regression analysis showed that opioid epidural analgesia (OR 3.0, 95% CI 1.2 to 7.2, P = .02) was associated with good quality of recovery, whereas Cob breeds (OR 0.16, 95% CI 0.06 to 0.46, P = .001), age (in years) (OR 0.90, 95% CI 0.83 to 0.97, P = .004) increasing intraoperative dosages (in mg/kg) of thiopental (OR 0.64, 95% CI 0.46 to 0.90, P = .01) or ketamine (OR 0.42, 95% CI 0.18 to 0.98, P = .04) were associated with poor quality of recovery. MAIN LIMITATIONS:Certain variables that may influence quality of recovery, such as patient temperament and hindlimb orthopaedic co-morbidities were not recorded. The clinical prediction model obtained is only applicable to the specific facilities, population and perianaesthetic management practiced at our institution. CONCLUSIONS:Opioid epidural analgesia is significantly associated with good quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis. Other risk factors, such as increasing age, cob breed, use of higher intraoperative dosages (in mg/kg) of ketamine and/or thiopental, were associated with poor quality of recovery.

Equine Veterinary EducationVolume 32, Issue 6 p. 311-312 Clinical Commentary Decision making with keratomas: How advanced imaging can advance your cause P. I. Milner, Corresponding Author pmilner@liverpool.ac.uk orcid.org/0000-0002-5293-2438 Veterinary Sciences, University of Liverpool, Neston, Wirral, UKCorresponding author email: pmilner@liverpool.ac.ukSearch for more papers by this author P. I. Milner, Corresponding Author pmilner@liverpool.ac.uk orcid.org/0000-0002-5293-2438 Veterinary Sciences, University of Liverpool, Neston, Wirral, UKCorresponding author email: pmilner@liverpool.ac.ukSearch for more papers by this author First published: 24 December 2018 https://doi.org/10.1111/eve.13032Read the full textAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume32, Issue6June 2020Pages 311-312 RelatedInformation

Identification and characterization of foreign bodies in the distal limb of horses poses a diagnostic challenge. The aims of this prospective experimental cadaver study were to describe the appearance of five foreign body materials within the equine hoof using CT, MRI, and digital radiography (DR) and to compare interrater agreement among three reviewers. Fifty foreign bodies consisting of five materials were implanted at a solar location or a coronary location in 25 equine cadaver feet. The images were reviewed by three equine veterinarians experienced in advanced imaging interpretation, who were blinded to the material of the foreign body. Foreign bodies were graded on visibility and appearance. Sensitivity and specificity were calculated for accurate identification of the different materials. Interrater agreement was assessed using Fleiss' kappa. Computed tomography had higher visibility score, sensitivity/specificity, and interrater agreement for detection of all materials; particularly slate, glass, and dry wood, compared to the other imaging modalities. Soaked wood and plastic had lower sensitivity (31-33%) on CT with a similar attenuation of the two materials. Foreign bodies were often visible on MRI, although with similar appearance and unclear details. On DR, only slate and glass were visible. The interrater agreement for identifying the correct material was almost perfect for slate, glass, and dry wood (κ = 0.92-1.00) and poor for plastic and soaked wood (κ < 0.20) on CT. Interrater agreement was poor for all materials on MRI and DR (κ < 0.20), with the except for fair (κ = 0.28) for slate on DR and moderate (κ = 0.28) for soaked wood on MRI.

Summary Background Strangulating small intestinal disease ( SSID ) carries a poor prognosis for survival in comparison to other types of colic, particularly if resection is required. Identification of markers which aid early diagnosis may prevent the need for resection, assist with more accurate prognostication and/or support the decision on whether surgical intervention is likely to be successful, would be of significant welfare benefit. Objectives To apply an unbiased methodology to investigate the plasma and peritoneal fluid proteomes in horses diagnosed with SSID requiring resection, to identify novel biomarkers which may be of diagnostic or prognostic value. Study design Prospective clinical study. Methods Plasma and peritoneal fluid from horses presented with acute abdominal signs consistent with SSID was collected at initial clinical examination. Samples from eight horses diagnosed with SSID at surgery in which resection of affected bowel was performed and four control horses subjected to euthanasia for orthopaedic conditions were submitted for liquid chromatography tandem mass spectrometry. Protein expression profiles were determined using label‐free quantification. Data were analysed using analysis of variance to identify differentially expressed proteins between control and all SSID horses and SSID horses which survived to hospital discharge and those which did not. Significance was assumed at P≤0.05. Results A greater number of proteins were identified in peritoneal fluid than plasma of both SSID cases and controls, with 123 peritoneal fluid and 13 plasma proteins significantly differentially expressed ( DE ) between cases and controls (P<0.05, ≥2 fold change). Twelve peritoneal fluid proteins (P<0.036) and four plasma proteins (P<0.05) were significantly DE between SSID horses which survived and those which did not. Main limitations A low number of samples were analysed, there was variation in duration and severity of SSID and only short‐term outcome was considered. Conclusions Changes in peritoneal fluid proteome may provide a sensitive indicator of small intestinal strangulation and provide biomarkers relevant to prognosis.

Purpose: Human umbilical cord-derived mesenchymal stromal cells (hUC-MSC) are promising candidates for allogeneic therapies, as they are multipotent cells with multi-lineage differentiation properties and potent immunomodulatory properties. We report the use of a modified murine partial medial meniscectomy model (PMM) to investigate the effect of hUC-MSCs on osteoarthritis (OA) progression in a xenogeneic model. Specifically, we have investigated whether transplanted hUC-MSCs elicit an inflammatory response or alter the effects of OA progression by assessing the articular cartilage, subchondral bone and synovium of murine knee joints. Methods: Male, ten week old C57Bl/6 mice (n=91) underwent a sham surgery (n=15) or modified PMM surgery (n=76) in the left hind limb. Three and six weeks post-injury 5x105 hUC-MSCs (isolated from three individual UC donors, Donors 1-3) were injected intra-articularly and joints were harvested eight and twelve weeks post-injury, respectively. Sham groups and PMM controls (both receiving no cells) were included at both time points. Histomorphometric analyses of the knee joints were obtained using micro-computed tomography (μ-CT) and the OARSI semi-quantitative scoring system was used to assess the histopathology throughout the knee joint on safranin-O and fast green stained sections (minimum of 8 sections per knee, 10μm apart). These were scored by three scorers, to yield a max score (0-6) for each of the four joint quadrants (medial femoral condyle (MFC), medial tibial plateau (MTP), lateral femoral condyle (LFC) and lateral tibial plateau (LTP) throughout the knee joint. A summed score (0-72, where a higher score signifies increased joint degeneration) was also obtained from the highest three scoring sections per knee. Synovitis was also scored by three scorers, on one H&E-stained section midway through the joint. The inflammatory markers, interleukin 6 (IL-6), IL-1beta, IL-4, IL-10, interferon-gamma (IFN-y), monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-alpha (TNF-a) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were analysed using custom mesoscale discovery (MSD) biomarker assays in murine plasma at the 12-week time point. Results: Micro-CT analysis revealed osteoarthritic changes in all the PMM joints, with joint space narrowing and osteophyte formation. The median joint space following PMM on the medial side in the control group was significantly less than in the sham operated knees at eight weeks (PMM=4.5μm, sham=42.8μm; p=0.02) and at 12 weeks (PMM=0μm; sham=51.8μm; p=0.0003). The injection of hUC-MSCs from the three cord donors resulted in variable outcomes in the treated mice. PMM-operated mice (n=8 at 12 weeks) that received hUC-MSCs from Donor 1 had a significantly (p=0.02) preserved joint space compared with the PMM control; this significance was not seen at 8 weeks, whereas Donors 2 and 3 showed no significance at either time point. All PMM treatment groups had a greater number of osteophytes than sham operated knees at the 8 week time point, whilst at 12 weeks, only joints that received hUC-MSCs from Donor 3 and the PMM control had significantly more osteophytes than the sham control. Hence Donors 1 and 2 showed no significant difference to the sham control. There were only minimal changes observed in the epiphyseal subchondral bone thickness and bone:total volume at both time points across all treatment groups. All PMM groups (with and without implantation of hUC-MSCs) had a significantly higher (worse) summed joint score than the sham control at 8 weeks, but there was no significant difference at 12 weeks. When looking at the maximum scores for the medial vs the lateral aspects of the joint, the scores for the medial femoral condyles and tibial plateau were also significantly different for all the PMM groups compared to the sham at 8 weeks, but not at 12 weeks. At both time points there were no significant differences on the lateral side. There was also no difference in synovitis scores between any of the experimental groups or controls at either time point. Additionally, no increase in inflammatory markers was detected in the plasma of treated mice compared to sham or controls. Conclusions: These results demonstrate that the PMM model effectively induced advanced OA in the operated mice. Whilst transplanting hUC-MSCs did not reduce the damage to the joint induced by PMM as assessed histologically, the implanted cells did not appear to elicit an inflammatory response in the treated mice, at least at the time points studied here. Furthermore, there appears to be a difference in UC donors, with one of the three UC-MSC populations significantly preserving joint space at the 12 week time point. This suggests that some populations may have the potential for eliciting joint preservation, indicating that characterisation of donors is likely to be important in developing allogeneic cell therapies.

Purpose: CCN2 is a matricellular protein which has been shown to be heavily involved in several complex biological processes including angiogenesis, fibrosis, and chondrogenesis. CCN2 is known to be expressed in both healthy and osteoarthritic cartilage, and involved in the production of the major cartilage matrix proteins; aggrecan and collagen type II. CCN2 null mice have been reported to exhibit a range of skeletal dysmorphisms, highlighting the importance of CCN2 in regulating matrix formation and turnover. The aim of this study was to determine the function of CCN2 in chondrocytes postnatally, in models of trauma-induced osteoarthritis (OA). Methods: Three double transgenic mouse models were generated; two inducible CCN2 knockout (KO) lines and one inducible CCN2 overexpressing (O/E) line. Both CCN2 KO lines contained Aggrecan CreERT2 enhancers which enabled the deletion of CCN2 from different populations of chondrocytes, whilst the O/E line contained an UbcCCN2-IRES-LacZ transgene enabling CCN2 O/E in all chondrocytes. CCN2 deletion and overexpression was induced following tamoxifen treatment in males aged 8 weeks. OA was induced either through surgical injury (transection of the medial meniscus and medial menisco-tibial ligament), or non-invasively by applying a controlled loading regimen to the tibio-femoral joint at 10 weeks of age. Knee joints were harvested and fixed, scanned with μCT, and processed for histology. Sections were stained with Toluidine Blue and scored for articular cartilage degeneration using the OARSI grading system. Results: In the surgical model of OA, cartilage degeneration was most severe on the medial side of the joint, however no significant differences were observed between lesion severity in wildtype (WT) and KO at any of the time-points analysed (2, 4, and, 8 weeks post-surgery). In the non-invasive model of OA lesion severity was most severe on the lateral femur in both the KO and O/E lines. As with the surgical model, no differences in lesion severity were observed between WT / KO and WT / O/E when analysed 6 weeks post-loading. μCT analysis of trabecular bone BV/TV and joint space in both models showed no effect of CCN2 KO and O/E between WT and experimental animals. Conclusions: CCN2 did not appear to play a protective role in the development of OA irrespective of whether the damage was induced surgically or non-invasively. The progression and severity of OA in both models, at all time-points, suggests the expression of CCN2 specifically in chondrocytes is not enough to protect articular cartilage from the degeneration associated with trauma-induced OA.