Osteogenic and Chondrogenic Potential of Periosteum-Derived Mesenchymal Stromal Cells: Do They Hold the Key to the Future?

The periosteum, with its outer fibrous and inner cambium layer, lies in a dynamic environment with a niche of pluripotent stem cells for their reparative needs. The inner cambium layer is rich in mesenchymal progenitors, osteogenic progenitors, osteoblasts, and fibroblasts in a scant collagen matrix environment. Their role in union and remodeling of fracture is well known. However, the periosteum as a source of mesenchymal stem cells has not been explored in detail. Moreover, with the continuous expansion of techniques, newer insights have been acquired into the roles and regulation of these periosteal cells. From a therapeutic standpoint, the periosteum as a source of tissue engineering has gained much attraction. Apart from its role in bone repair, analysis of the bone-forming potential of periosteum-derived stem cells is lacking. Hence, this article elucidates the role of the periosteum as a potential source of mesenchymal stem cells along with their capacity for osteogenic and chondrogenic differentiation for therapeutic application in the future.

Role of FBXW2 in explant cultures of bovine periosteum-derived cells

Objective Bone regeneration is a potential technique for treating osteoporosis. A previous study reported that F-box and WD-40 domain-containing protein 2 (FBXW2) localized with osteocalcin in bovine periosteum after 5 weeks of explant culture. However, the osteoblastic functions of FBXW2 remain unclear. In this study, double-fluorescent immunostaining was used to investigate the potential role of FBXW2 and its relationship with osteocalcin. Results At day 0, FBXW2 was expressed in the cambium layer between the bone and periosteum, while osteocalcin was expressed in bone. After explant culture, changes in the periosteum were observed from weeks 1 to 7. At week 1, partial FBXW2 expression was seen with a small amount of osteocalcin. At week 2, a layer of FBXW2 was observed. From weeks 3 to 7, tube-like structures of FBXW and osteocalcin were observed, and periosteum-derived cells were released from the periosteum in areas where no FBXW2 was observed. Bovine periosteum-derived cells can form a three-dimensional cell pellet, because multilayered cell sheets are formed inside of the periosteum in vitro. It is shown that in results FBXW2 is produced in periosteal explants near sites where initial osteogenic activity is observed, suggesting that it may be involved in periosteal osteogenesis.

Isolation and Characterization of Female Rabbit Periosteal Derived Progenitor Cells

Background Periosteum is a specialized highly vascularized connective tissue that is formed of an external fibrous layer containing collagen fibers and micro vessels and an inner cambium layer that facing the bone. Cambium layer includes periosteum derived progenitor cells (PDPCs) which have osteochondrogenic potential both in vitro and in vivo and act as major players in bone development and fracture healing. Periosteum derived progenitor cells display properties of mesenchymal stem cells (MSCs), including clonogenicity, phenotypic marker expression, and ability to differentiate into osteoblasts, chondrocytes and adipocytes. So, they are recognized to be essential for the initiation of bone graft healing and remodeling, but their clinical application is still limited due to inaccessibility. The aim of the present study is isolation, culture and characterization of rabbit’s PDPCs. Methods twenty-five adult female rabbits were used to harvest periosteal samples. Cell cultures were obtained by migration of cells from periosteal fragments (explant culture). Immunostaining of the cells of PDPCs in subculture (third passage) was performed. Result On day three of primary culture, the PDPCs were not started to migrate from the periosteal explant edges. However, on day six of primary culture, few spindle PDPCs cells appeared at the edge of explant. on day 20 of primary culture, PDPCs were mostly confluent ( about 9095%) . Immunostaining of PDPCs in subculture (third passage) showed positive brownish reaction of the branched cells for CD105 and CD44 and negative immune reaction for both CD34 and CD45. Conclusion The current study yielded isolation and cultured of female rabbit Periosteal derived progenitor cells. Periosteal derived stem cells are display properties of mesenchymal stem cells (MSCs), including clonogenicity, phenotypic marker expression.

Microcutting Redox Profile and Anatomy in Eucalyptus spp. With Distinct Adventitious Rooting Competence

Adventitious root (AR) development takes place in an intricate cellular environment. Reactive oxygen species (ROS) and antioxidant defenses, triggered by wounding in cuttings, can modulate this process. A comparative assessment of biochemical and anatomical parameters at critical rooting stages in hard- (Eucalyptus globulus Labill.) and easy- (Eucalyptus grandis W.Hill ex Maiden) to-root species was carried out. Microcuttings from seedlings were inoculated in auxin-free AR induction medium and, after 96 h, transferred to AR formation medium for a period of 24 h. Samples were collected upon excision (Texc) and at the 5th day post excision (Tform). Delayed xylem development, with less lignification, was recorded in E. globulus, when compared to E. grandis, suggesting lower activity of the cambium layer, an important site for AR development. Superoxide was more densely present around the vascular cylinder at both sampled times, and in greater quantity in E. globulus than E. grandis, declining with time in the former. Hydrogen peroxide was localized primarily along cell walls, more intensely in the primary xylem and phloem, and increased significantly at Tform in E. globulus. Ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT) activities were generally higher in E. grandis and varied as a function of time in E. globulus. Soluble guaiacol peroxidase (GPRX) activity increased from Texc to Tform in both species, whereas cell wall-bound GPRX activity increased with time in E. grandis, surpassing E. globulus. Flavonoid content increased with time in E. grandis and was higher than E. globulus at Tform. Principal component analysis showed that species- and time-derived differences contributed to almost 80% of the variance. Overall, data indicate that E. grandis shows higher cambium activity and tighter modulation of redox conditions than E. globulus. These features may influence ROS-based signaling and phytohormone homeostasis of cuttings, thereby impacting on AR development. Besides being players in the realm of AR developmental differences, the specific features herein identified could become potential tools for early clone selection and AR modulation aiming at improved clonal propagation of this forest crop.

Periosteum: The forgotten source of osteoprogenitors

Bone is one of the few tissues capable of authentic regenerative repair. However, despite advances in surgical technique, orthopaedic hardware and our understanding of fracture biology, inadequate bone repair remains a major concern in both veterinary and human medicine. Cell-based technologies provide opportunities to utilize the osteogenic capacities of Mesenchymal Stem Cells (MSC) to augment bone repair. Much of the research on MSC biology has focused on cells derived from the bone marrow/endosteal compartment; however, osteoprogenitor cells (OPC) also reside in the periosteum. Periosteum develops as a fibro-cellular envelope surrounding developing skeletal elements. The inner, or cambium layer of periosteum, includes committed OPCs directly adjacent the bone surface, and a distinct sub-population of progenitors within the periosteal mid-substance that retain both chondrogenic and osteogenic capacities. During skeletogenesis, periosteal OPCs are responsible for appositional intramembranous bone formation that increases the radial diameter of long bones. Of critical importance, periosteal stem cells are the predominant cell population responsible for generating the cartilaginous or ‘soft’ callus that provides intermediate stabilization and a scaffold for subsequent callus ossification by endochondral ossification; the primary mechanism of bone repair. In recent experiments using isolates from ‘donor-matched’ periosteum and bone marrow, we have found that the basal osteogenic capacity of equine OPCs is considerably less than that of bone marrow-derived MSCs. Periosteal OPCs require exogenous Bone Morphogenetic Protein (BMP) for robust osteogenesis, a finding consistent with the clinical responses of bone to recombinant BMP protein. Perhaps more surprising, the osteogenic capacity of adult (2-10 years of age) OPCs is comparable to those of young foals’, although the cell yield is considerably greater from foal specimens. In light of the vital importance of callus formation for successful fracture healing of most, further research on the biology and clinical manipulation of periosteal OPCs is highly warranted.

Investigation of Fungi Causing Twig Blight Diseases on Peach Trees in South Carolina

A survey of fungal pathogens causing twig blight on commercial peach trees was conducted in South Carolina in the fall of 2016. Shoots with cankers, pycnidia, and dieback were collected from six locations around the state. Isolates obtained from these samples were identified as Botryosphaeria obtusa, Phomopsis amygdali, Leucostoma persoonii, and Cytospora sp., based on colony morphology, conidia size and shape, and ribosomal DNA sequence analysis. L. persoonii was the most prevalent species and was isolated in five of the six locations, followed by P. amygdali and B. obtusa. The sensitivity of representative isolates of B. obtusa, P. amygdali, and L. persoonii to fungicides of different FRAC codes was evaluated. All species tested were sensitive to thiophanate-methyl (FRAC 1) and pyraclostrobin and azoxystrobin (both FRAC 11), whereas all species were resistant to boscalid and fluopyram (both FRAC 7). P. amygdali and B. obtusa were sensitive to difenoconazole and propiconazole (both FRAC 3), whereas L. persoonii was moderately resistant. L. persoonii was the most virulent species based on expansion of mycelium in the cambium layer of 2-year-old, detached twig pieces. Bacterial spot (BS)-sensitive cultivar ‘O’Henry’ was most susceptible to B. obtusa compared with BS-sensitive ‘Summerprince’, brown rot (BR)-resistant ‘Contender’, and BR-sensitive ‘Coronet’ but was least susceptible to L. persoonii. Coronet was most susceptible to L. persoonii. There were no significant differences between susceptibility of the cultivars to P. amygdali. This study established that L. persoonii is currently the most frequent twig blight pathogen in South Carolina, perhaps owing to its superior fitness. Some fungicides were effective in controlling all twig blight pathogens and may therefore be useful for chemical management strategies. Our study also provides the first evidence that the genetic basis of resistance to BS and BR in peach trees is not necessarily linked to tolerance to wood pathogens.

Effect of Anatomical Structure of Shoots in Different Flowering Phase on Rhizogenesis of Once-blooming Roses

The research was conducted on five once-blooming different origin historical roses. The aims were establishing differences in the anatomical structure of shoots taken in four maturity stages and their natural ability to roots creating. There were hypothesized, that the changes in anatomical structure occur in the time of flowering and may affect the ability of rhizogenesis. Single node one leaf cuttings of chosen cultivars were cut from shoots in four maturity phases: flower buds closed, all flowers open, just after and 7-14 days after petal fall. The cuttings were planted in multipot trays in peat substrate without using rooting stimulators. The anatomical structure of shoots in the place of rhizogenesis were observed, the width of xylem layer and cambial zone, diameter of vascular cells were measured. The percentage of rooted cuttings and forming only a callus were counted. Adventitious roots appeared probably in the cambium zone, pith rays, and also in the zone of phloem and pericycle. The anatomic structure of shoots changes during the period of flowering and influences rooting percentage and the percent of cuttings which developed callus only. The width of the cambium layer of shoots influences the width of the wood layer in all cultivars. The rise of width of cambium tissue have an effect of increase of percentage of cuttings forming a callus only in ‘Hurdals’ and ‘Maiden’s Blush’. The width of the cambium layer in shoots enlarges during full blooming in four of the studied cultivars (‘Hurdals’, ‘Maiden’s Blush’, ‘Mousseuse Rouge’, ‘Semiplena’) and in one it stays at the same level for the whole duration of the experiment (‘Duchesse d’Angoulême’). The specifying in practice the period of taking rose cuttings, individual properties of cultivars and phenological phase of shoot should be taken into consideration.

Morpho-histological analysis of tomato (Solanum lycopersicum L.) plants after treatment with juglone

Juglone is a substance that limits plant growth and has a toxic effect on plant development. In this study, we analyzed the influence of juglone at two different concentrations (10⁻³ M and 10⁻⁴ M), which were applied to different parts of <em>Solanum lycopersicum</em> L. plants (root system, stem after decapitation, and surface of a younger leaf or after autografting) for a short period of time (7 days), on the morphology and histology of stems. At a lower concentration, juglone had positive effects on plant growth, which resulted in an increase in interfascicular cambial cell divisions, faster development of a continuous cambium layer along the stem circumference, and development of fibers. Additionally, under the influence of juglone, the number of developing leaves increased and adventitious roots developed. The results are discussed based on the current literature concerning the reaction of plants to juglone and to stress conditions.

Fibrillation of events in the cambial domains of Tilia cordata Mill.

The cambium and 9 annual growths from a linden stem were studied. Some of the fusiform cell ends changed their contacts-which is shown by the comparison of the cambium layer and terminal parenchyma of the phloem. This means that these ends were active in the period the layers under comparison were formed. The active ends were found in groups numbering a few to ten-odd ends alternating with groups of inactive ends. About 70% of the ends retained their activity for only one year. In the studied areas. in a given year, one direction of migration of the active ends dominated. As a rule, this configuration changed every two years. Along with the change in the configuration of the active ends, the position of the active areas also changed in such a way that after the change of configuration, the areas previously inactive became active. No migration of activity along the borders of the storeys was observed, but only its appearance and disappearance, which was called fibrillation of activity. Fibrillation of activity becomes noticeable when there is a low intensity of events. Because the active areas at a given moment are characterized by one type of configuration of events, the whole studied surface can be seen as a single domain. Fibrillation gives the impression of frequent changes of domain type, these changes, however, are of a different nature than the movement of domain borders found in cambium characterized by a high intensity of events.

Adrenal gland pathology in rats after acute postnatal hypoxia

Aim. To study the histological changes in the adrenal glands of rats with acute postnatal hypoxia and «structural trace» in the adrenal glands during the first month of life. Methods. Wistar rats were used as experimental animals. After calving, the newborn rats (main group, 20 newborn rats, progeny of 5 female rats) were placed in the bell-pressure chamber (simulating altitude of 3.500 meters with an atmospheric pressure of 493 mm Hg) for 5 min. Rats were withdrawn from the experiment by decapitation at the first day (1 hour after the acute postnatal hypoxia modeling, 7 rats), 7 days after (7 rats) and 35 days after (6 rats) the experiment. The same number of intact rats of the control group were examined at the same timepoints. The adrenal glands of rats were examined morphologically using histological, histochemical, immunohistochemical and morphometric methods. Results. It was found that a short episode of mild short hypoxia just after the birth leads to the development of specific adaptive changes in adrenal glands: cortical hyperplasia, increased morpho-functional activity of endocrinocytes in the medullar substance associated with extensive apoptosis, decreasing of morpho-functional activity of endocrinocytes of the glomerular zone and fetal cortex. Cellular regeneration of spongiocytes was observed not only in the cambium layer, but also in the fascicular zone, which presumes not only physiological, but also reparative regeneration. Regeneration of medullar cells, seemingly, only occurs during the first few days after birth by migration of sympathogonia from outside of the adrenal gland to its center. At days 14 th and 35 th, despite the same conditions, histological signs of active functioning of the cortical fascicular zone and medullar substance preserved in animals of the main group compared with the controls. Conclusion. Results of the study prove the need for clinical studies of the adrenal function correction in newborns undergoing postnatal and intranatal acute hypoxia, as well as of consequences for the adrenal gland morpho-functional state after birth for such cases.