Daiki Murata

Isolation and characterization of equine dental pulp stem cells derived from Thoroughbred wolf teeth

Mesenchymal stem cells (MSCs) are adult multipotent stem cells that are capable of self-renewal and differentiation into multiple cell lineages. Methods for cell therapy using MSCs have been developed in equine medicine. Recently, human dental pulp stem cells (DPSCs) have drawn much attention owing to their trophic factor producing ability and minimally invasive collection methods. However, there have been no reports on equine dental pulp-derived cells (eDPCs). Therefore, the aim of this study was to isolate and characterize the eDPCs from discarded wolf teeth. Plastic-adherent spindle-shaped cells were isolated from wolf teeth. The doubling time of the isolated eDPCs was approximately 1 day. Differentiation assays using induction medium eDPCs differentiated into osteogenic, chondrogenic and adipogenic lineages. The eDPCs expressed mesenchymal makers (CD11a/18, CD44, CD90 CD105 and MHC class I and II), but did not express hematopoietic markers (CD34 and CD45). Taken together, the results show that eDPCs can be isolated from discarded wolf teeth, and they satisfy the minimal criteria for MSCs. Thus, these eDPCs can be referred to as equine DPSCs (eDPSCs). These eDPSCs may become a new source for cell therapy.

Characteristics and multipotency of equine dedifferentiated fat cells

ABSTRACT Dedifferentiated fat (DFAT) cells have been shown to be multipotent, similar to mesenchymal stem cells (MSCs). In this study, we aimed to establish and characterize equine DFAT cells. Equine adipocytes were ceiling cultured, and then dedifferentiated into DFAT cells by the seventh day of culture. The number of DFAT cells was increased to over 10 million by the fourth passage. Flow cytometry of DFAT cells showed that the cells were strongly positive for CD44, CD90, and major histocompatibility complex (MHC) class I; moderately positive for CD11a/18, CD105, and MHC class II; and negative for CD34 and CD45. Moreover, DFAT cells were positive for the expression of sex determining region Y-box 2 as a marker of multipotency. Finally, we found that DFAT cells could differentiate into osteogenic, chondrogenic, and adipogenic lineages under specific nutrient conditions. Thus, DFAT cells could have clinical applications in tissue regeneration, similar to MSCs derived from adipose tissue.

Isolation of equine peripheral blood stem cells from a Japanese native horse

ABSTRACT The sizes of Japanese native horses have drastically decreased, and protection of these populations is important for Japanese horse culture. Social trials as well as scientific attempts are necessary for maintaining the breed. Mesenchymal stem cells (MSCs) have potential as a cell source for various cell therapies. However, there have been no reports on MSCs of Japanese native horses. We aimed to isolate and characterize MSCs from a Japanese native horse, the Noma horse. Plastic-adherent and self-replicating cells were isolated from a Noma horse’s peripheral blood (PB). The isolated cells had trilineage potential and a surface antigen of mesenchymal cells, so they fulfilled the minimal criteria of MSCs. Therefore, PB can be one source of MSCs for Japanese native horses.

A study of the distribution of color Doppler flows in the superficial digital flexor tendon of young Thoroughbreds during their training periods

ABSTRACT Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated in 3 longitudinal images of equal lengths (labelled 1, 2, 3 in order from proximal to distal), and 6 transversal images separated by equal lengths (labelled 1A, 1B, 2A, 2B, 3A and 3B in order from proximal to distal) of the metacarpus using both GS and CD. The running (canter and gallop) distance for 1 month before the date of the ultrasonographic examinations was increased in December, February, and April in both of the two training periods. CD flows defined as rhythmically blinking or pulsatory colored signals were found in 56 of 864 (6.4%) transversal CD images, in 28, 12, 13, and 3 images of 1A, 1B, 2A and 2B, respectively, and in 7, 14, and 35 images captured in December, February, and April, respectively. There were no longitudinal or transversal GS images indicating injury in the SDFTs in either of the two training periods. The increase of CD flows in the proximal regions of the SDFT are possibly related to the increase of the running distance during the training periods of the one- to two-year-old Thoroughbreds. Because no injury was diagnosed in the SDFTs by GS images during the training periods, the increase of CD flows in the proximal parts of SDFT is not necessarily predictive of tendon injury in the near future during the training period of young Thoroughbreds.

Osteochondral Regeneration of the Loading-bearing Site Using a Scaffold Free Three-dimensional Construct of Adipose Tissue-derived Mesenchymal Stem Cells in Pigs

Background: Many surgical strategies for reconstruction of both bone and cartilage have ever been investigated to restore joint structure and function in the late stages of Osteoarthritis (OA). This study was designed to investigate the regeneration of articular cartilage and subchondral bone in the loading-bearing site using a three-dimensional (3D) construct of autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs). Methods: A 3D construct consisting of approximately 1,920 spheroids each containing 5.0 × 104 AT-MSCs was implanted into an osteochondral defect (with a diameter of 6.8 mm and a depth of 6 mm) in the right femoral medial condyle in five adult mini-pigs. The contralateral (left femoral) defect was the control. At three and six months post-operatively, the defects were evaluated using both CT and MR imaging. The radiolucent volume (RV, mm3) of the defects was calculated based on the multiplanar reconstruction of the CT images. MR images and gross and histologic pathology features were scored using a modified-MOCART system and the ICRS system, respectively, at six months post-operatively. Results: The percentages of RVs at three and six months compared with those immediately after the surgeries were significantly decreased in the implanted defects compared with the control defects. The total scores of modified- MOCART system were also significantly increased in the implanted sites comparing to the controls. Although there were no statistical differences in the average of gross scores, the average histological scores were significantly higher in the implanted sites than in the control sites. Conclusion: This is the first report suggesting that implantation of a scaffold-free three dimensional construct of only AT-MSCs into the osteochondral defect regenerates the original cartilage and subchondral bone structures over six months post-operatively in the loading-bearing site of large animal.

Ganglion Cysts Arising from a Canine Stifle Joint

ABSTRACT A 10-year-old, neutered male Labrador retriever presented with progressive left hind lameness. Ultrasonography revealed large, subcutaneous, ovoid cysts around the stifle joint. Radiographic and computed tomographic images revealed periosteal reaction of the distal femur. Magnetic resonance (MR) imaging showed a large cyst that was hypointense in T1-weighted images, hyperintense in T2-weighted images and had a thin lining that was enhanced by intravenous gadonium injection. The cyst communicated with the joint cavity and other small cysts around the joint. Histopathology of an excisional biopsy specimen led to diagnosis of ganglion cyst. This report provides MR images of a ganglion cyst in a canine stifle.