Hematopoietic bone marrow cells participate in endothelial, but not epithelial or mesenchymal cell renewal in adult rats

The extent to which bone marrow (BM) contributes to physiological cell renewal is still controversial. Using the marker human placental alkaline phosphatase (ALPP) which can readily be detected in paraffin and plastic sections by histochemistry or immunohistochemistry, and in ultrathin sections by electron microscopy after pre-embedding staining, we examined the role of endogenous BM in physiological cell renewal by analysing tissues from lethally irradiated wild-type inbred Fischer 344 (F344) rats transplanted (BMT) with unfractionated BM from ALPP-transgenic F344 rats ubiquitously expressing the marker. Histochemical, immunohistochemical and immunoelectron microscopic analysis showed that the proportion of ALPP+ capillary endothelial cells (EC) profoundly increased from 1 until 6 months after BMT in all organs except brain and adrenal medulla. In contrast, pericytes and EC in large blood vessels were ALPP–. Epithelial cells in kidney, liver, pancreas, intestine and brain were recipient-derived at all time-points. Similarly, osteoblasts, chondrocytes, striated muscle and smooth muscle cells were exclusively of recipient origin. The lack of mesenchymal BM-derived cells in peripheral tissues prompted us to examine whether BMT resulted in engraftment of mesenchymal precursors. Four weeks after BMT, all haematopoietic BM cells were of donor origin by flow cytometric analysis, whereas isolation of BM mesenchymal stem cells (MSC) failed to show engraftment of donor MSC. In conclusion, our data show that BM is an important source of physiological renewal of EC in adult rats, but raise doubt whether reconstituted irradiated rats are an apt model for BM-derived regeneration of mesenchymal cells in peripheral tissues

Anatomy, histology, development and functions of Ossa cordis: A review

This systematic review highlights the similarities and variations in Ossa cordis prevalence, histology and anatomical location between differing veterinary species and in humans. In addition, it also identifies associated factors such as aging and cardiovascular disease for each species in relation to functional roles and developmental mechanisms that these bone structures may play. The potential functions of Ossa cordis are presented, ranging from aiding cardiac contraction and conduction, providing cardiac structure, and protecting components of the heart, through to counteracting high mechanical stress. Furthermore, this review discusses the evidence and rationale behind the theories regarding the formation and development of Ossa cordis in different veterinary species and in people

Bones in the heart skeleton of the otter (Lutra lutra)

In most mammalian species the cardiac skeleton is composed of coarse collagen fibres, fibrocartilage, and pieces of hyaline cartilage. Bone, the os cordis, is a regular constituent of the ruminant heart. The cardiac skeleton of the otter (Lutra lutra) has not previously been described. The skeleton in 30 otter hearts was studied by x-ray analysis and light microscopy. Serial sections were cut parallel to the atrioventricular plane and histochemical staining methods were performed to identify connective tissue fibres, glycosaminoglycans, mineral deposits, and bone. Age and sex of the animals under investigation were considered. The otter heart skeleton was composed of coarse collagen fibres with intercalated pieces of fibrous and/or hyaline cartilage, calcified cartilage, and lamellar bone with red or white marrow. Pieces of hyaline cartilage were not clearly defined: a perichondrial layer was missing and coarse connective tissue continuously transformed into fibrous and hyaline cartilage. In both sexes the amount of cartilage and bone were found to increase with age. Our results establish the presence of bony material in the heart skeleton of the otter, a small mammalian species. This finding indicates that differentiation of bone is not exclusively related to the size of the organ. Increasing amounts of calcified cartilage and bone correlated with increasing age

The Expression of Uncoupling Protein 3 Coincides With the Fatty Acid Oxidation Type of Metabolism in Adult Murine Heart

The involvement of mitochondrial uncoupling proteins 2 and 3 in the pathogenesis of cardiovascular diseases is widely acknowledged. However, contradictory reports show that the functions of UCP2/UCP3 are still disputed. We have previously described that UCP2 is highly abundant in cells that rely on glycolysis, such as stem, cancer and activated immune cells. In contrast, high amounts of UCP3 are present in brown adipose tissue, followed by heart and skeletal muscles - all known to metabolize fatty acids (FA) to a high extent. Using two different models – mouse embryonic stem cell (mESC) differentiation to cardiomyocytes (CM) and murine heart at different developmental stages – we now tested the concept that the expression ratio between UCP2 and UCP3 indicates the metabolism type in CM. Our results revealed the tight correlation between UCP3 abundance, expression of mitochondrial fatty acid oxidation (FAO) markers and presence of multiple connections between mitochondria and lipid droplets. We further demonstrated that the time course of UCP3 expression neither coincided with the onset of the electrical activity in CM, derived from mESC, nor with the expression of respiratory chain proteins, the observation which rendered protein participation in ROS regulation unlikely. The present data imply that UCP3 may facilitate FAO by transporting FAs into mitochondria. In contrast, UCP2 was highly abundant at early stages of heart development and in mESC. Understanding, that the expression patterns of UCP3 and UCP2 in heart during development reflect the type of the cell metabolism is key to the uncovering their different functions. Their expression ratio may be an important diagnostic criterion for the degree of CM differentiation and/or severity of a heart failure.Peer Reviewe

Anatomical Evidence of Acupuncture Meridians in the Human Extracellular Matrix: Results from a Macroscopic and Microscopic Interdisciplinary Multicentre Study on Human Corpses

For more than 2500 years, acupuncture has been applied to support the healing of different diseases and physiologic malfunctions. Although various theories of the meridian system and mechanisms were formulated to explain the functional basis of acupuncture, the anatomical basis for the concept of meridians has not been resolved. The aim of the present study was to search for replicable anatomical structures that could relate to meridians. To this end, four human specimens and additionally two lower legs were dissected anatomically. Our study found evidence that acupuncture meridians were part of the human extracellular matrix and that fascia was an important part of the anatomic substrate of acupuncture meridians. At the same time, we found vessel-nerve-bundles, which were hypothesized to account for 80% of acupuncture points, only in a few acupuncture points. Therefore, our findings contradict the theory that acupuncture points are only located along the nervous channels

Muscle Fibre Architecture of Thoracic and Lumbar Longissimus Dorsi Muscle in the Horse

As the longissimus dorsi muscle is the largest muscle in the equine back, it has great influence on the stability of the spine and facilitates proper locomotion. The longissimus muscle provides support to the saddle and rider and thereby influences performance in the horse. Muscular dysfunction has been associated with back disorders and decline of performance. In general, muscle function is determined by its specific intramuscular architecture. However, only limited three-dimensional metrical data are available for the inner organisation of the equine longissimus dorsi muscle. Therefore, we aimed at investigating the inner architecure of the equine longissimus. The thoracic and lumbar longissimus muscles of five formalin-fixed cadaveric horse backs of different ages and body types were dissected layerwise from cranial to caudal. Three-dimensional coordinates along individual muscle fibre bundles were recorded using a digitisation tool (MicroScribe®), to capture their origin, insertion and general orientation. Together with skeletal data from computed tomography (CT) scans, 3D models were created using imaging software (Amira). For further analysis, the muscle was divided into functional compartments during preparation and morphometric parameters, such as the muscle fascicle length, pennation angles to the sagittal and horizontal planes, muscle volume and the physiological cross-sectional area (PCSA), were determined. Fascicle length showed the highest values in the thoracic region and decreased from cranial to caudal, with the cranial lumbar compartment showing about 75% of cranial fascicle length, while in most caudal compartments, fascicle length was less than 50% of the fascicle length in thoracic compartments. The pennation angles to the horizontal plane show that there are differences between compartments. In most cranial compartments, fascicles almost run parallel to the horizontal plane (mean angle 0°), while in the caudal compartment, the angles increase up to a mean angle of 38°. Pennation angles to the sagittal plane varied not only between compartments but also within compartments. While in the thoracic compartments, the fascicles run nearly parallel to the spine, in the caudal compartments, the mean angles range from 0–22°. The muscle volume ranged from 1350 cm3 to 4700 cm3 depending on body size. The PCSA ranged from 219 cm2 to 700 cm2 depending on the muscle volume and mean fascicle length. In addition to predictable individual differences in size parameters, there are obvious systemic differences within the muscle architecture along the longissimus muscle which may affect its contraction behaviour. The obtained muscle data lay the anatomical basis for a specific biomechanical model of the longissimus muscle, to simulate muscle function under varying conditions and in comparison to other species

Fetal Immunomodulatory Environment Following Cartilage Injury—The Key to CARTILAGE Regeneration?

Fetal cartilage fully regenerates following injury, while in adult mammals cartilage injury leads to osteoarthritis (OA). Thus, in this study, we compared the in vivo injury response of fetal and adult ovine articular cartilage histologically and proteomically to identify key factors of fetal regeneration. In addition, we compared the secretome of fetal ovine mesenchymal stem cells (MSCs) in vitro with injured fetal cartilage to identify potential MSC-derived therapeutic factors. Cartilage injury caused massive cellular changes in the synovial membrane, with macrophages dominating the fetal, and neutrophils the adult, synovial cellular infiltrate. Correspondingly, proteomics revealed differential regulation of pro- and anti-inflammatory mediators and growth-factors between adult and fetal joints. Neutrophil-related proteins and acute phase proteins were the two major upregulated protein groups in adult compared to fetal cartilage following injury. In contrast, several immunomodulating proteins and growth factors were expressed significantly higher in the fetus than the adult. Comparison of the in vitro MSCs proteome with the in vivo fetal regenerative signature revealed shared upregulation of 17 proteins, suggesting their therapeutic potential. Biomimicry of the fetal paracrine signature to reprogram macrophages and modulate inflammation could be an important future research direction for developing novel therapeutics

Co-culture of osteochondral explants and synovial membrane as in vitro model for osteoarthritis.

The purpose of the current study was to establish an in vitro model for osteoarthritis (OA) by co-culture of osteochondral and synovial membrane explants. Osteochondral explants were cultured alone (control-1) or in co-culture with synovial membrane explants (control-2) in standard culture medium or with interleukin-1β (IL1β) and tumor necrosis factor (TNFα) added to the culture medium (OA-model-1 = osteochondral explant; OA-model-2 = osteochondroal-synovial explant). In addition, in OA-model groups a 2-mm partial-thickness defect was created in the centre of the cartilage explant. Changes in the expression of extracellular matrix (ECM) genes (collagen type-1 (Col1), Col2, Col10 and aggrecan) as well as presence and quantity of inflammatory marker genes (IL6, matrix metalloproteinase-1 (MMP1), MMP3, MMP13, a disintegrin and metalloproteinase with-thrombospondin-motif-5 (ADAMTS5) were analysed by immunohistochemistry, qPCR and ELISA. To monitor the activity of classically-activated pro-inflammatory (M1) versus alternatively-activated anti-inflammatory/repair (M2) synovial macrophages, the nitric oxide/urea ratio in the supernatant of osteochondral-synovial explant co-cultures was determined. In both OA-model groups immunohistochemistry and qPCR showed a significantly increased expression of MMPs and IL6 compared to their respective control group. ELISA results confirmed a statistically significant increase in MMP1and MMP3 production over the culturing period. In the osteochondral-synovial explant co-culture OA-model the nitric oxide/urea ratio was increased compared to the control group, indicating a shift toward M1 synovial macrophages. In summary, chemical damage (TNFα, IL1β) in combination with a partial-thickness cartilage defect elicits an inflammatory response similar to naturally occurring OA in osteochondral explants with and without osteochondral-synovial explant co-cultures and OA-model-2 showing a closer approximation of OA due to the additional shift of synovial macrophages toward the pro-inflammatory M1 phenotype