Diagnostic performance of a rapid immunochromatographic test for the simultaneous detection of antibodies to Theileria equi and Babesia caballi in horses and donkeys

BACKGROUND

Equine piroplasmosis is caused by two tick-borne protozoan parasites, Theileria equi and Babesia caballi,, which are clinically relevant in susceptible horses, donkeys, and mules. Moreover, equine piroplasmosis significantly constrains international trading and equestrian events. Rapidly diagnosing both parasites in carrier animals is essential for implementing effective control measures. Here, a rapid immunochromatographic test for the simultaneous detection of antibodies to T. equi and B. caballi was evaluated using samples from horses and donkeys collected in Greece, Israel, and Italy. The results were compared with an improved competitive enzyme-linked immunosorbent assay (cELISA) for detecting antibodies to both parasites using the same panel of samples.

METHODS

Blood samples were collected from 255 horses and donkeys. The panel consisted of 129 horses sampled at four locations in northern Greece, 105 donkeys sampled at four locations in Sicily, and 21 horses sampled at two locations in Israel. The rapid test and the cELISA were performed according to the manufacturer's instructions, and the results were subjected to a statistical analysis to determine the sensitivity and specificity of both tests and their association.

RESULTS

The immunochromatographic test provided a result within 15 min and can be performed in the field, detecting both pathogens simultaneously. The overall coincidence rate between the rapid test and the cELISA for detecting antibodies against T. equi was 93% and 92.9% for B. caballi. The rapid test's sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for T. equi were above 91.5%. Sixteen samples were positive for both parasites in the rapid test and eight in the cELISA. Either test had no significant association between T. equi and B. caballi detection. The detection rates of both parasites were significantly higher in Italy than in Greece or Israel and in donkeys than in horses. The agreement for T. equi between the results of both tests was high in Greece (93.8%) and Italy (95.2%) and moderate in Israel (76.2%). For B. caballi, the specificity and NPV of the rapid test were high (94.2% and 98.3%, respectively), although the sensitivity and PPV were moderate (69.2% and 39.1%, respectively) due to the small sample size. However, for B. caballi, the sensitivity was higher with the rapid test.

CONCLUSIONS

The rapid test detected T. equi and B. caballi simultaneously in the field, potentially replacing laborious cELISA testing and is recommended for import/export purposes. The test can also be helpful for the differential diagnosis of clinical cases, since seropositivity may rule out equine piroplasmosis since it does not indicate current or active infection.

Biomolecular Analysis of Canine Distemper Virus Strains in Two Domestic Ferrets (Mustela putorius furo)

Canine distemper is a contagious and severe systemic viral disease that affects domestic and wild carnivores worldwide. In this study, two adult female ferrets (Mustela putorius furo) were evaluated for cutaneous lesions. Scab, fur, and swab samples from the external auditory canal, cutaneous lesions, and scrapings were analyzed. Canine distemper virus (CDV)-positive samples underwent RT-PCR/RFLP with the restriction enzyme PsiI, and the hemagglutinin gene sequence was obtained. According to the restriction enzyme and sequence analyses, the viral strains were typed as CDV field strains that are included within the Europe lineage and distinct from those including vaccinal CDV strains. The sequence analysis showed the highest nucleotide identity rates in older Europe lineage CDV strains collected from dogs and a fox in Europe. This study is the first to report on CDV infection in ferrets in southern Italy and contributes to the current knowledge about natural CDV infection in this species. In conclusion, vaccination remains crucial for preventing the disease and counteracting cross-species infection. Molecular biology techniques can enable the monitoring of susceptible wild animals by ensuring the active surveillance of CDV spread.

A Review on the Immunological Response against Trypanosoma cruzi

Chagas disease is a chronic systemic infection transmitted by Trypanosoma cruzi. Its life cycle consists of different stages in vector insects and host mammals. Trypanosoma cruzi strains cause different clinical manifestations of Chagas disease alongside geographic differences in morbidity and mortality. Natural killer cells provide the cytokine interferon-gamma in the initial phases of T. cruzi infection. Phagocytes secrete cytokines that promote inflammation and activation of other cells involved in defence. Dendritic cells, monocytes and macrophages modulate the adaptive immune response, and B lymphocytes activate an effective humoral immune response to T. cruzi. This review focuses on the main immune mechanisms acting during T. cruzi infection, on the strategies activated by the pathogen against the host cells, on the processes involved in inflammasome and virulence factors and on the new strategies for preventing, controlling and treating this disease.

Persistence of DNA from canine parvovirus modified-live virus in canine tissues

Canine parvovirus (CPV-2) modified-live virus vaccine strain can replicate in lymphoid tissues and intestinal mucosa after administration, being shed through canine faeces. Detection of vaccine strains has been reported in the bloodstream and faeces, potentially interfering with molecular diagnostic tests. The persistence of these strains in canine tissues has not yet been described. With this aim, canine tissues were tested during a molecular survey to screen for the presence of canine enteric viruses. Tissue samples from 165 dead dogs were tested by a conventional PCR assay. Positive samples and five commercial vaccines were subjected to sequence analysis. Vaccinal strains were detected and virus load was measured by using a set of real-time PCR assays using minor-groove binder (MGB) probes. Seventy-five dogs (45.4%) tested positive for CPV-2. Strains from 70 dogs were characterised as field variants. The presence of CPV sequences of vaccine origin was observed in the spleen, intestine, and mesenteric lymph nodes of five young dogs. Vaccinal strains were detected from 12 to 24 days after the last vaccine administration. Viral loads comprised between 6.3 × 10² and 9.95 × 10⁴ DNA copies/10 µl of template. This study confirms that CPV vaccinal strains can be detected in canine tissues after vaccination, so post-mortem diagnosis of CPV infection needs further molecular analyses to assess the viral type (vaccine or field strains). The present study updates the current information on the persistence of CPV vaccine strains in canine tissues and their possible interference with molecular assays.

Study on the Canine Adenovirus Type 1 (CAdV-1) Infection in Domestic Dogs in Southern Italy

Canine adenovirus type 1 (CAdV-1) is the causative agent of a systemic and potentially fatal viral disease of domestic and wild canids. In Italy, CAdV-1 infection has also been occasionally described in dogs, but information on the epidemiology and its genomic features is still limited. A study was conducted on 291 dogs suspected of infectious gastrointestinal disease. Samples collected from dogs in southern Italy between 2017 and 2020 were analyzed. Virological and histopathological assays were carried out. The presence of CAdVs and other canine viral enteropathogens was investigated, and sequence and phylogenetic analyses were performed. CAdV-1 was detected in six (2.1%) dead stray dogs alone or in mixed infections with other viruses. Gross lesions and histopathological findings referred to CAdV infection were observed, also involving the central nervous system tissues. All inoculated samples were successfully isolated. Sequence analysis evidenced divergences with the circulating strains previously described in Italy and a closer relation with older CAdV-1 strains collected from other countries, suggesting a genetic heterogeneity of CAdV-1 in Italy. The evidence of the circulation of CAdV-1 and its genomic features allows us to have more in-depth knowledge of the epidemiology and evolution of the CAdV-1 genomic variants.

Agreement between In-Clinics and Virus Neutralization Tests in Detecting Antibodies against Canine Distemper Virus (CDV)

Core vaccinations and specific antibody titer evaluations are strongly recommended worldwide by all the vaccination guidelines. Virus neutralization (VN) is considered the gold standard for measuring antibody titer against canine distemper virus, but it is complex and time consuming, and the use of in-clinics tests would allow to obtain quicker results. The aim of this study was to evaluate the agreement of the commercial in-clinics VacciCheck test compared to VN. A total of 106 canine sera were analyzed using both methods. The best agreement was obtained using a protective threshold of ≥1:32. VacciCheck showed 95.5% sensitivity, 87.2% specificity, and 92.5% accuracy. The Cohen’s kappa coefficient between methods was 0.84 (CI 95% 0.73 to 0.95), revealing an optimal agreement between the two methods (p = 0.0073). The evaluation of discordant results reveal that most samples had less than 1.5 dilution difference, and that usually did not affect the classification as protected or non-protected. Results also suggest that, in dubious cases, especially when a protective result is expected, retesting is advisable. In conclusion, VacciCheck may be considered as a reliable instrument that may help the clinician in identifying the best vaccine protocol, avoiding unnecessary vaccination, and thus reducing the incidence of adverse effects.

Hepatitis E Virus seroprevalence among cows in a rural area of southern Italy

Hepatitis E virus (HEV) is considered to be an emerging zoonotic disease, which causes numerous cases of hepatitis and deaths worldwide each year. Pigs are a host reservoir of HEV, but numerous other wild and domestic species can be infected. The aim of this study was to carry out serological screening of anti-HEV antibodies in cattle in the Sicily region (Southern Italy). Between April and December 2018, 231 serum samples were collected from cows and analysed with enzyme-linked immunosorbent assay (ELISA), for detection of HEV antibodies (IgG). The overall prevalence of anti-HEV antibodies was 36.36% (84/231; 95% CI 30-43). There were statistically significant differences in the HEV seroprevalence in animals of different ages (<11 months: 11.41%; >12 months: 39.30%; >24 months: 54.10%) (P<0.05). No statistically significant differences were detected between genders (31.37% in male and 37.38% in female) (P >0.05). This study shows that further investigation of HEV in cattle is required to understand better the epidemiology in farm animals and the potential zoonotic risks for humans. This is the first report of HEV seroprevalence for cows in Italy, which provides baseline data for further studies and for control of HEV infection in cattle.

First neuroinvasive human case of West Nile Disease in Southern Italy: Results of the 'One Health' approach

Background

West Nile Disease (WND) is a zoonotic mosquito‐borne infection involving viral pathogens, human and animal hosts, vectors and environment. Cooperation among medical, veterinary and entomological fields has been promoted by the Italian Public Health Authorities, and an integrated West Nile Virus (WNV) Surveillance Plan has been in force in Italy since 2016 to prevent the transmission risk of WND to humans through an early detection of viral circulation by animal and entomological surveillance. This managing model is unique in Europe.

Objectives

This survey aimed at presenting the ‘One Health’ approach applied in 2016 to the first autochthonous human case of West Nile Neuroinvasive Disease (WNND) in Sicily (Southern Italy).

Methods

Serological (anti‐WNV IgM and IgG ELISA, anti‐WNV neutralizing antibodies) and molecular tests were conducted on blood, liquor and urine of a 38‐year‐old man with encephalitis and meningitis. Overall, 2704 adult culicides from 160 mosquito catches were morphologically identified. Female mosquitoes were analysed in pools for WNV RNA detection. Serological (anti‐WNV IgM and IgG ELISA) and molecular analyses for WNV were carried out in 11 horses, 271 chickens and two dogs sampled in farms around the man's residence.

Results and conclusions

WNND was confirmed by serological analysis on patient's liquor and serum. Collected mosquito species included Culex pipiens (93.56%, CI_95% 92.64%–94.49%), Aedes albopictus (5.25%, CI_95% 4.41%–6.09%), Culex hortensis (0.59%, CI_95% 0.30%–0.88%), Culiseta longiareolata (0.55%, CI_95% 0.27%–0.83%) and Anopheles maculipennis s.l. (0.04%, CI_95% –0.04% to 0.11%). Mosquito pools were negative for WNV RNA. Two dogs (100%) and two horses (18.18%, CI_95% –4.61 to 40.97%) resulted positive for anti‐WNV specific antibodies.

The ‘One Health’ approach allowed to report the first human neuroinvasive WND in Sicily and to confirm the local circulation of WNV in animals of the same area where the clinical case occurred, defining the autochthonous origin of the infection.

Detection and Molecular Characterization of Two Gammaherpesviruses from Pantesco Breed Donkeys during an Outbreak of Mild Respiratory Disease

Equid and asinine gammaherpesviruses (GHVs; genus Percavirus) are members of the Herpesviridae family. Though GHVs have been reported in horse populations, less studies are available on gammaherpesviral infections in donkeys. This study reports the co-infection with two GHVs in Pantesco breed donkeys, an endangered Italian donkey breed. Samples (n = 124) were collected on a breeding farm in Southern Italy from 40 donkeys, some of which were healthy or presented erosive tongue lesions and/or mild respiratory signs. Samples were analysed by using a set of nested PCRs targeting the DNA polymerase, glycoprotein B, and DNA-packaging protein genes, and sequence and phylogenetic analyses were performed. Twenty-nine donkeys (72.5%) tested positive, and the presence of Equid gammaherpesvirus 7 and asinine herpesvirus 5 was evidenced. In 11 animals, we found evidence for co-infection with viruses from the two species. Virions with herpesvirus-like morphology were observed by electron microscopic examination, and viruses were successfully isolated in RK-13-KY cell monolayers. The histological evaluation of tongue lesions revealed moderate lympho-granulocytic infiltrates and rare eosinophilic inclusions. The detection of GHVs in this endangered asinine breed suggests the need long-life monitoring within conservation programs and reinforces the need for further investigations of GHV’s pathogenetic role in asinine species.

The Effect of a 7 Year-Long Cryopreservation on Stemness Features of Canine Adipose-Derived Mesenchymal Stem Cells (cAD-MSC)

Mesenchymal stem cells (MSCs) are used in therapy in animal models and veterinary medicine, due to their capacity of inducing tissue regeneration and immunomodulation. Their clinical application requires a ready off-the-shelf amount of viable therapeutics doses. For this purpose, it is useful to cryopreserve MSCs to gain a ready and controlled source of abundant autologous stem cells. We evaluated the effect of 7 years cryopreservation using 10% dimethyl sulfoxide (DMSO) with different fetal bovine serum (FBS) concentrations (from 10 to 90%) on different passages of MSCs isolated from canine adipose tissue (cAD-MSCs). The study aimed to evaluate the most adequate cell passage and FBS percentage for the long-term cryopreservation of cells by maintaining the stemness features. Phenotype morphology, cell viability, osteogenic and adipogenic differentiation potentials, proliferative potential and expression of pluripotency markers were analyzed in thawed cells and compared with fresh ones. We demonstrated that cells cryopreserved with at least 80% FBS maintain unaltered the stemness characteristics of the freshly isolated cells. In particular, cells of P0-P1 passages have to be expanded in vitro and subsequently cryopreserved and cells of P2-P4 passages should be considered in the studies on therapeutic application and in vitro study of cAD-MSCs.

Serological and Molecular Evidence of Bartonella henselae in Stray Cats from Southern Italy

Bartonella henselae is a slow growing and facultative intracellular pathogen mainly transmitted by arthropod vectors adapted to domestic and wild mammalian reservoir hosts. Since cats are the major source of the B. henselae infection, this study aimed to evaluate the seroprevalence and the DNA presence in randomly sampled stray cats. Blood samples of 429 cats were collected from shelter of Palermo (Southern Italy) and sera and whole blood were analyzed for the presence of antibodies against B. henselae by indirect immunofluorescence assay (IFA) and by real-time polymerase chain reaction (PCR), respectively. Two hundred and three sera (47.3%) were positive to IFA and 148 blood samples (34.5%) to real-time PCR. Based on serological results, the evaluation of the potential risk factors (sex, age, coat color) was carried out. The multivariate analysis indicated that cats more than 12 months old were more likely to be seropositive to B. henselae than cats <12 months. These data will add useful information to the understanding of the spread of B. henselae in stray cats in Southern Italy.

Current status and risk factors of canine parvovirus type 2 in North Central Nigeria

Since its emergence in Nigeria, canine parvovirus type 2 (CPV-2) infection has posed problems to dog breeding and requires constant awareness and monitoring. In this study, the status, the assessment of extrinsic risk factors of parvoviral infection in dog kennels in North Central Nigeria, and isolation of the CPV-2 were carried out. Potential risk factors were considered during sampling: age, breed, sex, location, vaccination and health status, using well-structured questionnaires on dog owners with experience of CPV-2 infection. There was high prevalence which depended on age, breed, location, clinical status of the dog while vaccination status of the dogs did not influence the prevalence. CPV-2 vaccination compliance by the breeders and management system of the kennels were also observed as risk factors. Isolation of CPV-2a and -2c strains from Nigeria for further study has been reported. The spread of CPV-2 in Nigeria is increasing, hence needs for continual epidemiological monitoring and review.

Seroprevalence of Borrelia burgdorferi in Stray Dogs from Southern Italy

Borrelia burgdorferi is a bacterial pathogen transmitted by Ixodes ticks and is responsible for Lyme disease in both humans and dogs. The aim of this work was to evaluate B. burgdorferi diffusion among stray dogs in Palermo (Sicily, Italy) by serological methods in order to study the risk factors associated with the infection. Serum and blood samples of 316 dogs were collected from a shelter in Palermo, and were analyzed for the presence of antibodies against B. burgdorferi by indirect immunofluorescence assay (IFA), and of the ospA gene by real-time PCR, respectively. Seventeen sera (5.4%) were positive for the antibodies via IFA and one blood (0.3%) for ospA via real time PCR. On the basis of serological results, the evaluation of the potential risk factors (sex, age, breed and coat color) was carried out. The multivariate analysis indicated that male sex is a factor significantly associated with B. burgdorferi seropositivity. This study confirms that male dogs have a higher risk of developing the disease than females, and represents the first investigation on the spread of B. burgdorferi among stray dogs in Sicily.

Molecular epidemiology of canine parvovirus type 2 in Italy from 1994 to 2017: recurrence of the CPV-2b variant

Background

Canine parvovirus type 2 (CPV-2) is the most important enteric virus infecting canids. It is a rapidly evolving virus; after its emergence in the 1970s, new antigenic variants (called CPV-2a, 2b and 2c) emerged and replaced the original antigenic type. The three antigenic variants are globally distributed with different frequencies and levels of genetic variability. This study focused on VP2 gene sequence analysis and the phylodynamics of CPV-2 which were detected in 123 dogs showing clinical signs of gastroenteritis collected in Italy from 1994 to 2017.

Results

For the most part, the sick dogs were young, and a third of them (32.5%) had been vaccinated. No statistical association was found between the CPV-2 antigenic variants, and sex, age, breed and vaccination status. Sequence analysis showed that all three antigenic types circulated in Italy; the CPV-2a type was the prominent genotype, followed by CPV-2c and CPV-2b, with notable differences regarding regional bases and significant fluctuations over time. Nucleotide sequence data showed high genetic heterogeneity with 67 nucleotide sequence types (ntSTs) identified, corresponding to 21 amino acid sequence types (aaSTs). The aaSTs and ntSTs obtained were distributed differently among the three CPV-2 antigenic variants: CPV-2a grouped 12/21 (57.1%) aaSTs and 41/67 (61.2%) ntSTs; CPV-2b grouped 5/21 (23.8%) aaSTs and 6/67 (8.9%) ntSTs, and CPV-2c grouped 4/21 (19.1%) aaSTs and 20/67 (29.9%) ntSTs. Canine parvovirus 2a was characterised by the highest genetic variability while CPV-2c was characterised by notable stability with a predominant amino acid profile during the entire sampling time. Canine parvovirus 2b re-emerged in recent years, showing a new and distinctive amino acid profile of the VP2 protein.

Conclusions

The findings of the present study provided new insights regarding the phylodynamics and evolution of CPV-2 in Italy, pointing out notable differences at the local level in the distribution of the CPV-2 variants and the selection of genetic subtypes. The evolution of CPV-2 has raised questions regarding the efficacy of vaccination; therefore, continuous monitoring regarding the evolution and spread of new CPV-2 variants should be a key aim of ongoing research.

Nearly full-length genome characterization of canine parvovirus strains circulating in Nigeria

Canine parvovirus type 2 (CPV‐2) emerged suddenly in the late 1970s as pathogen of dogs, causing a severe and often fatal gastroenteric disease. The original CPV‐2 was replaced by three antigenic variants, CPV‐2a, CPV‐2b and CPV‐2c, which to date have gained a worldwide distribution with different relative proportions. All previous studies conducted in Africa were based on partial VP2 gene sequences. The aim of this study was to provide a genome analysis to characterize the CPV strains collected in Nigeria, Africa. Rectal swab samples (n = 320) were collected in 2018 and tested by means of an immunochromatographic assay. Among the 144 positive samples, 59 were selected for further analyses using different molecular assays. The results revealed a high prevalence of CPV‐2c (91.5%) compared to the CPV‐2a variant (8.5%). The VP2 gene sequences showed a divergence from the strains analysed in 2010 in Nigeria and a closer connection with CPV strains of Asian origin. The non‐structural gene analysis evidenced amino acid changes never previously reported. The molecular analysis based on genomic sequences evidenced a geographical pattern of distribution of the analysed strains, suggesting a potential common evolutionary origin with CPV of Asian origin. This study represents the first CPV molecular characterization including all the encoding gene sequences conducted in the African continent and contributes to define the current geographical spread of the CPV variants worldwide.

Spreading of canine parvovirus type 2c mutants of Asian origin in southern Italy

Canine parvovirus type 2 (CPV‐2) emerged as dog pathogen in the late 1970s, causing severe and often fatal epizootics of gastroenteritis in the canine population worldwide. Although to date CPV‐2 is circulating in all continents, most of the current studies have analysed the amino acid changes accounted in the VP2 gene sequence, with limited information on virus introductions from other countries. The aim of this study was to analyse the genetic features of CPV‐2c strains currently spreading in Italy. Swabs and tissue samples were collected from dogs suspected of CPV infection. The nearly complete genome sequence from the CPV‐positive samples was obtained. The co‐circulation of two different but related CPV‐2c strains, with amino acid changes characteristic of CPV strains of Asian origin (NS1: 60V, 544F, 545F, 630P – NS2: 60V, 151N, 152V ‐ VP2: 5A/G, 267Y, 297A, 324I, 370R), were observed. The phylogenetic analyses inferred from the NS1 and VP2 gene sequences confirmed the relationship with Asian CPV‐2c strains. This study reports the spread of novel CPV‐2c mutants in Italy and supports further studies to evaluate the coexistence of genetically divergent CPV strains in the same geographical environment.

Update on canine distemper virus (CDV) strains of Arctic-like lineage detected in dogs in Italy

Canine distemper virus (CDV) is the etiologic agent of distemper in dogs. It exhibits an elevated potential of crossing species barriers, infecting a wide range of wild and domestic carnivores. Of its encoding genes, hemagglutinin (H) shows high heterogeneity, and it was used to determine the relationship between CDV strains due to its variability and key role in determining cell tropism, host shift, and in eliciting a protective immune response. This study analysed the full-length H gene sequence of Arctic-like CDV strains collected from dogs in Italy during a period in which an increased activity of CDV diffusion was observed. The common amino acid changes and features of Arctic-like CDV strains collected from 2011 to 2016 in Europe were described, providing an updated analysis of the genomic features. A comparison with CDV vaccine strains was carried out to evaluate the increased genomic difference with CDV Arctic-like field strains. This study provides a complete and updated analysis of the current spreading strains of Arctic-like lineage and the main amino acid variations in the hemagglutinin gene sequence circulating in Italy. Moreover, it provides novel information regarding the evolution of the most recent CDV Arctic-like lineage strains collected in Europe.

Molecular typing of a novel canine parvovirus type 2a mutant circulating in Italy

Canine parvovirus (CPV) is the etiological agent of a severe viral disease of dogs. After its emergence in late 1970s, the CPV original type (CPV-2) was rapidly and totally replaced by three antigenic variants named CPV-2a, CPV-2b and CPV-2c. CPV has an evolutionary rate nearest to those of RNA viruses, with consequences on disease diagnosis and epidemiology. This paper reports the molecular characterization of eight CPV-2a strains collected from dogs in Italy in 2016–2017. Genetic analysis was conducted on a CPV genomic region encompassing both open reading frames (ORFs) encoding for nonstructural (NS1-NS2) and structural proteins (VP1-VP2). Sequence analysis indicates new and unreported sequence changes, mainly affecting the VP2 gene, which included the mutation Tyr324Leu. This study represents the first evidence of a new CPV-2a mutant (VP2 324Leu) and illustrates the importance of a continuous molecular survey in order to obtain more information on effective spread of new CPV mutants.

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Canine parvovirus strains collected from dogs in southern Italy were analyzed.

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Nearly complete genome sequences of the CPV strains were obtained and comparatively analyzed.

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A novel CPV-2a mutant with unreported sequence changes has been characterized.

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This study reports a novel CPV-2a mutant in genus Protoparvovirus.

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Our data confirmed the importance of the continuous epidemiological survey.

Canine mesenchymal stem cells (MSCs): characterization in relation to donor age and adipose tissue-harvesting site

Adipose tissue as a stem cell source is ubiquitously available and has several advantages compared to other sources, for example it is easily accessible in large quantities with minimal invasive harvesting procedure, and isolation of adipose-derived mesenchymal stem cells (MSCs) yields a high amount of stem cells, essential for stem cell-based therapies and tissue engineering. We have explored the effect of donor age, and the anatomical origin of the adipose tissue on several aspects of MSCs in dogs, such as cell yield, proliferative ability, multi-differentiation potential, colony-forming capacity, stemness marker expression. We also assessed the effect of cell passaging on the MSCs stemness. We found that the anatomical origin of the adipose tissue and the age of donors have effects only on the proliferative capacity of the MSCs. Moreover, cells show a progressive loss of the stemness characteristics with passages. Cell therapies need a suitable number of cells to use in clinical applications. Characterization of MSCs at different passages, allowed us to demonstrate that, under our culture conditions, the best quantitative and qualitative characteristics are obtained at early passages. Adult MSCs are of particular interest for the therapeutic approach to musculoskeletal diseases, and the dog provides an excellent preclinical model for the development of new approaches in regenerative medicine that might be applied to humans.

Modeling human osteosarcoma in mice through 3AB-OS cancer stem cell xenografts

Osteosarcoma is the second leading cause of cancer-related death for children and young adults. In this study, we have subcutaneously injected-with and without matrigel-athymic mice (Fox1nu/nu) with human osteosarcoma 3AB-OS pluripotent cancer stem cells (CSCs), which we previously isolated from human osteosarcoma MG63 cells. Engrafted 3AB-OS cells were highly tumorigenic and matrigel greatly accelerated both tumor engraftment and growth rate. 3AB-OS CSC xenografts lacked crucial regulators of beta-catenin levels (E-cadherin, APC, and GSK-3beta), and crucial factors to restrain proliferation, resulting therefore in a strong proliferation potential. During the first weeks of engraftment 3AB-OS-derived tumors expressed high levels of pAKT, beta1-integrin and pFAK, nuclear beta-catenin, c-Myc, cyclin D2, along with high levels of hyperphosphorylated-inactive pRb and anti-apoptotic proteins such as Bcl-2 and XIAP, and matrigel increased the expression of proliferative markers. Thereafter 3AB-OS tumor xenografts obtained with matrigel co-injection showed decreased proliferative potential and AKT levels, and undetectable hyperphosphorylated pRb, whereas beta1-integrin and pFAK levels still increased. Engrafted tumor cells also showed multilineage commitment with matrigel particularly favoring the mesenchymal lineage. Concomitantly, many blood vessels and muscle fibers appeared in the tumor mass. Our findings suggest that matrigel might regulate 3AB-OS cell behavior providing adequate cues for transducing proliferation and differentiation signals triggered by pAKT, beta1-integrin, and pFAK and addressed by pRb protein. Our results provide for the first time a mouse model that recapitulates in vivo crucial features of human osteosarcoma CSCs that could be used to test and predict the efficacy in vivo of novel therapeutic treatments.