Skeletal muscle regeneration induced by chorio-allantoic grafting

Increasing Follicular and Stromal Cell Proliferation in Cryopreserved Human Ovarian Tissue after Long-Term Precooling Prior to Freezing: In Vitro versus Chorioallantoic Membrane (CAM) Xenotransplantation

A positive effect on the future development of cells, which have been cooled to low suprazero temperatures and then thawed, has been observed before and is not new. The aim of this study was to test the effectiveness of postthawing culture of human ovarian tissue, which was either frozen just after operative removal or cooled after removal to 5°C for 24 h before cryopreservation. Ovarian fragments from six patients were divided into small pieces in the form of cortex with medulla and randomly divided into the following four groups: Group 1 consisted of pieces that just after removal had been cultured in vitro for 8 days in a big volume of medium with mechanical agitation; Group 2 included pieces cooled after operation to 5°C for 24 h and then cultured in vitro for 8 days; Group 3 was comprised of pieces frozen–thawed just after operation and then cultured for 5 days in the chorioallantoic membrane (CAM) culture system; and the pieces in Group 4 were cooled after operation to 5°C for 24 h, frozen–thawed, and then cultured in the CAM system for 5 days. The effectiveness of the tissue culture was evaluated by the development of follicles and by the intensiveness of proliferation in the tissue (by expression of cytokeratin and Ki-67). For Groups 1, 2, 3, and 4, the mean densities of follicles per 1 mm3 was 12.9, 12.2, 12.4, and 16.1, respectively ( p1–2 > 0.1; p3–4 < 0.05). For these groups, 87%, 95%, 71%, and 84% of the preantral follicles were morphologically normal ( p1–2, 3–4 < 0.05). The immunohistochemical analysis showed increased proliferation after cooling of fresh and cryopreserved tissue. Long-term (24 h) cooling of ovarian tissue to 5°C before cryopreservation increases the viability of the cells in the tissue after thawing. Additionally, the efficacy of the CAM system for the culture of thawed human ovarian tissue was demonstrated.

Comparison of in vitro- and chorioallantoic membrane (CAM)-culture systems for cryopreserved medulla-contained human ovarian tissue

At present, there are three ways to determine effectively the quality of the cryopreservation procedure using ovarian tissue before the re-implantation treatment: evaluation of follicles after post-thawing xenotransplantation to SCID mouse, in-vitro culture in a large volume of culture medium under constant agitation and culture on embryonic chorio-allantoic membrane within a hen's eggs. The aim of this study was to compare the two methods, culture in vitro and culture on embryonic chorioallantoic membrane (CAM) of cryopreserved human ovarian medulla-contained and medulla-free cortex. Ovarian fragments were divided into small pieces (1.5–2.0×1.0–1.2×0.8–1.5) of two types, cortex with medulla and medulla-free cortex, frozen, thawed and randomly divided into the following four groups. Group 1: medulla-free cortex cultured in vitro for 8 days in large volume of medium with mechanical agitation, Group 2: medulla-containing cortex cultured in vitro, Group 3: medulla-free cortex cultured in CAM-system for 5 days, Group 4: medulla-containing cortex cultured in CAM-system. The efficacy of the tissue culture was evaluated by the development of follicles and by intensiveness of angiogenesis in the tissue (von Willebrand factor and Desmin). For Group 1, 2, 3 and 4, respectively 85%, 85%, 87% and 84% of the follicles were morphologically normal (P>0.1). The immunohistochemical analysis showed that angiogenesis detected by von Willebrand factor was lower in groups 1 and 3 (medulla-free cortex). Neo-vascularisation (by Desmin) was observed only in ovarian tissue of Group 4 (medulla-contained cortex after CAM-culture). It appears that the presence of medulla in ovarian pieces is beneficial for post-thaw development of cryopreserved human ovarian tissue. For medical practice it is recommended for evaluation of post-warming ovarian tissue to use the CAM-system as a valuable alternative to xenotransplantation and for cryopreservation of these tissues to prepare ovarian medulla-contained strips.

Liver reconstruction on the chorioallantoic membrane of the chick embryo

The liver from a 6-day-old chick embryo was transplanted on the chorioallantoic membrane of a 9-day-old chick embryo to observe the process of liver regeneration histologically. When a piece of the liver was implanted on the chorioallantoic membrane, only cells in the superficial zone of the graft adhering to the chorioallantoic membrane survived. Eventually, these surviving cells in the superficial zone proliferated with hematopoiesis, resulting in the formation of clusters of blood cells surrounded by the hepatocytes (or hepatic parenchymal cells). Semi-thin serial sections showed that these clusters of blood cells were confined to the space formed by hepatocytes. Furthermore, structures similar to the hepatic cord, sinusoid, central vein, and bile duct appeared in the reconstructed liver eleven days after transplantation. Meanwhile, when a pellet of the dissociated liver cells was transplanted onto the chorioallantoic membrane, two types of liver like structures were reconstructed: one was clusters of hepatocytes accompanied by sinusoids after hematopoiesis, and the other was a simple accumulation of hepatocytes without any sinusoids or hematopoiesis. The sinusoids found in the former type became clear following the connection between the space in the transplant and vessels of the chorioallantoic membrane. These findings indicated that the reconstructed liver was primarily produced by the accumulation of hepatocytes accompanied by hematopoietic cells, followed by the formation of sinusoidal spaces. We therefore consider that hematopoiesis is important for liver regeneration with a normal structure. Transplantation of the liver in the chorioallantoic membrane could be also useful for research into liver regeneration.

Chick embryo chorioallantoic membrane (CAM) model: a useful tool to study short-term transplantation of cryopreserved human ovarian tissue

OBJECTIVE

To investigate the chorioallantoic membrane (CAM) model for the study of short-term transplantation of frozen human ovarian tissue.

DESIGN

Prospective study.

SETTING

Academic research unit.

PATIENT(S)

Ovarian tissue was obtained from three women.

INTERVENTION(S)

Frozen-thawed human cortical fragments were grafted onto traumatized CAM or beneath the CAM of 10-day-old chick embryos. Grafts were retrieved after 1, 2, 3, 4, and 5 days in ovo.

MAIN OUTCOMES MEASURE(S)

Viability was assessed by calcein-AM and ethidium homodimer I. Tissue integrity, ischemic injury, and neovascularization were evaluated by histology. Cell proliferation was analyzed by Ki-67 immunohistochemistry.

RESULT(S)

All the grafts showed adhesion when placed onto CAM, compared with only 30.4% beneath the CAM. Follicles were healthy, apart from a few degenerated follicles in necrotic and fibrotic areas. After 5 days, the majority of follicles were intermediate (32%) or primary (45.7%). Ki-67 immunohistochemistry revealed 12.5% proliferative follicles on day 2, reaching 20.7% on day 5. Fibrosis appeared on day 1; necrosis, follicular degeneration and follicular proliferation on day 2; and neovascularization and stromal cell proliferation on day 3.

CONCLUSION(S)

The present study showed that the CAM model provides a new approach to study human ovarian tissue transplantation in its first ischemic stages, yielding information on the timing of tissue changes before the establishment of neovascularization.

Expression of multiple troponin T isoforms in chicken breast muscle regeneration induced by sub-serous implantation

Chicken fast-muscle type (F-type) troponin T (TnT) isoforms are classified into two types, leg-muscle type (L-type) and breast-muscle type (B-type), which are generated by exclusion and inclusion of exon x series-derived sequences in mRNAs, respectively. The B-type isoforms are further classified into neonatal breast-muscle (BN), young chicken breast-muscle (BC), and adult chicken breast-muscle (BA) subtypes. It is known that the multiple F-type TnT isoforms are transiently expressed in the breast muscle tissue during normal development. To examine whether the transition of the isoforms was fixed in muscle cell lineage, breast muscle pieces (pectoralis major) of 1-day old chicks were cultured under gizzard serous membrane of the same chicks for 60 days at the longest. TnT isoform expression of the implants was monitored by immunoblotting and immunostaining using anti-F-type TnT against both L-type and B-type isoforms, anti-exon x3 against only B-type isoforms, and anti-S-type TnT against slow-muscle-type (S-type) isoforms. Muscle fibers in the implant degenerated first, and then new myotubes expressing L-type isoforms were formed by the fusion of myoblasts from surviving satellite cells. When the maturation of the myotubes into myofibers proceeded, BN-, BC-, and BA-subtype isoforms were expressed in the order of developmental stage specific-manner, indicating that the order of appearance of these isoforms was fixed in muscle cell lineage. In immunostaining of the implants recovered on the 60th day after implantation, at least three kinds of the regenerated myofibers were observed, expressing mainly B-type, both B-type and L-type, and only L-type isoforms. The immunohistochemical results suggested that the regulation of alternative splicing of F-type TnT pre-mRNAs was different among individual myofibers, and that the regulation was programmed in myogenic cells, probably satellite cells, which were the primary source of the fibers.

Novel tissue culture method: skeletal muscle implantation under gizzard serous membrane of a chick

A novel method for a long-term culture of skeletal muscle is described. Skeletal muscle pieces from young chicks were implanted under the gizzard serous membrane of the same chicks. Following muscle degeneration, new well-grouped muscle fibers were formed by the fusion of myocytes that differentiated from surviving satellite cells, and the regenerated muscle tissues were maintained in position for longer than 60 days. The implants were in the vital circulatory system, receiving trophic and oxygen supplies, and are completely free from motor nerve innervation and cell contamination with exogenous muscle cells, not as in intra-muscular implantation. Therefore, this tissue culture method should be useful for studying skeletal muscle regeneration and maturation over a long period. Furthermore, osteogenesis and feather development were also found in the implants of embryonic limbs by using the same method. These observations showed that not only skeletal muscle tissues but also other tissues could be cultured under the gizzard serous membrane.