Which is better? Early versus delayed rehabilitation after arthroscopic rotator cuff repair.

PURPOSE: This study aimed to compare the 5-year clinical and functional outcomes, including repaired tendon healing status, between early and delayed rehabilitation after arthroscopic rotator cuff repair METHODS: A total of 75 patients with rotator cuff tears (less than 5 cm) underwent arthroscopic repairs over a 60-month period. Participants were randomly assigned to early and delayed postoperative rehabilitation groups with distinct protocols. Clinical and functional outcome measures included Constant score, University of California at Los Angeles (UCLA) score, visual analogue scale for pain and isokinetic dynamometer test for muscle strength recovery. Clinical and functional scores were compared between baseline and 5 years postoperatively. Radiologic assessment via magnetic resonance imaging was performed at a minimum of 12 months postoperatively for evaluations of tendon integrity and recurrent tears. RESULTS: Baseline characteristics showed no statistically significant differences between groups. Both groups demonstrated equivalent improvement in range of motion and pain scores with no statistical differences. Clinical scores improved significantly in both groups by postoperative 12 months and plateaued. At the postoperative 5-year mark, the early group showed better improvement in the visual analogue scale and UCLA score, while the delayed group had superior Constant scores. Postoperative magnetic resonance imaging revealed six recurrent tears, two in the early group and four in the delayed group, with no statistical differences. Muscle strength recovery showed no differences between the two groups. CONCLUSION: Both the early and the delayed rehabilitation groups showed similar outcomes in postoperative range of motion, functional scores, muscle strength recovery and tendon healing in the short- and mid-term follow-ups. LEVEL OF EVIDENCE: Level III.

Extracellular signal-regulated kinase 1/2 signaling pathway is required for endometrial decidualization in mice and human.

Decidualization is a crucial change required for successful embryo implantation and the maintenance of pregnancy. During this process, endometrial stromal cells differentiate into decidual cells in response to the ovarian steroid hormones of early pregnancy. Extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) are known to regulate cell proliferation and apoptosis in multiple cell types, including uterine endometrial cells. Aberrant activation of ERK1/2 has recently been implicated in the pathological processes of endometriosis and endometrial cancer. However, the function of ERK1/2 signaling during implantation and decidualization is still unknown. To determine the role and regulation of ERK1/2 signaling during implantation and decidualization, we examine ERK1/2 signaling in the mouse uterus during early pregnancy using immunostaining and qPCR. Interestingly, levels of phospho-ERK1/2 were highest within decidual cells located at the implantation sites. Expression levels of ERK1/2 target genes were also significantly higher at implantation sites, when compared to either inter-implantation sites. To determine if ERK1/2 signaling is also important during human endometrial decidualization, we examined levels of phospho-ERK1/2 in cultured human endometrial stromal cells during in vitro decidualization. Following treatment with a well-established decidualization-inducing steroidogenic cocktail, levels of phospho-ERK1/2 were markedly increased. Treatment with the ERK1/2 inhibitor, U0126, significantly decreased the expression of the known decidualization marker genes, IGFBP1 and PRL as well as inhibited the induction of known ERK1/2 target genes; FOS, MSK1, STAT1, and STAT3. Interestingly, the phosphorylation level of CCAAT/ enhancer binding protein ß (C/EBPß), a protein previously shown to be critical for decidualization, was significantly reduced in this model. These results suggest that ERK1/2 signaling is required for successful decidualization in mice as well as human endometrial stromal cells and implicates C/EBPß as a downstream target of ERK1/2.

Transformation of somatic cells into stem cell-like cells under a stromal niche.

To study the genomic plasticity of somatic cells without ectopic genetic manipulation, we cultured mouse fibroblasts with ovarian cells, embryonic fibroblasts of different strains, and parthenogenetic embryonic stem cells (ESCs). Of 41 trials, cell aggregation resembling nascent ESC colony from inner cell mass was detected in 9 cases (22%), and 6 cases (67%) yielded fibroblast-derived colonies with ESC morphology. Cells used in coculture provided the critical (P=0.0061) inducing factor for the aggregation. These colony-forming fibroblasts (CFFs) showed similar characteristics to those in ESCs and induced pluripotent stem cells (iPSCs), including pluripotency gene expression, in vitro differentiation, and teratoma formation. Furthermore, CFFs produced somatic chimera, although none showed germline chimerism. CFFs had a tetraploid-like karyotype, and their imprinting patterns differed from parthenogenetic ESCs, thereby confirming their nongermline transmissibility. We observed dysregulation of cell cycle-related proteins, as well as both homologous and heterologous recombination of genomic single-nucleotide polymorphisms in CFFs. Our observations provide information on somatic cell plasticity, resulting in stemness or tumorigenesis, regardless of colony-forming cell progenitors in the fibroblast population. The plasticity of somatic genomes under environmental influences, as well as acquisition of pluripotency by cell fusion, is also implicated.

Replacement of mouse embryonic fibroblasts with bone marrow stromal cells for use in establishing and maintaining embryonic stem cells in mice.

We have investigated the use of BMSC (bone marrow stromal cell) as a feeder cell for improving culture efficiency of ESC (embryonic stem cell). B6CBAF1 blastocysts or ESC stored after their establishment were seeded on to a feeder layer of either SCA-1+/CD45-/CD11b- BMSC or MEF (mouse embryonic fibroblast). Feeder cell activity in promoting ESC establishment from the blastocysts and in supporting ESC maintenance did not differ significantly between BMSC and MEF feeders. However, the highest efficiency of colony formation after culturing of inner cell mass cells of blastocysts was observed with the BMSC line that secreted the largest amount of LIF (leukaemia inhibitory factor). Exogenous LIF was essential for the ESC establishment on BMSC feeder, but not for ESC maintenance. Neither change in stem cell-specific gene expression nor increase in stem cell aneuploidy was detected after the use of BMSC feeder. We conclude that BMSC can be utilized as the feeder of ESC, which improves culture efficiency.

Embryonic stem cell-like cells established by culture of adult ovarian cells in mice.

OBJECTIVE: To suggest an alternative strategy for deriving histocompatible stems cells without undertaking genetic manipulation. DESIGN: Prospective approach using an animal model. SETTING: Stem cell and bioevaluation laboratory, Seoul National University. ANIMAL(S): F1 (C57BL6 X DBA2) and outbred (ICR) mice. INTERVENTION(S): Ovarian stroma cells of less than 40 mum in diameter were subcultured with fibroblast monolayer, and colony-forming cells were characterized. MAIN OUTCOME MEASURE(S): Stemness, genotype, and imprinted gene methylation. RESULT(S): Two-lines of colony-forming cells were established, which expressed markers specific for embryonic stem cells (ESC) and formed embryoid bodies and teratomas. Complete matching of microsatellite markers with the cell donor strain confirmed their establishment from ovarian tissue, and identification of both homozygotic and heterozygotic chromosomes raised the possibility of their derivation from parthenogenetic oocytes. However, the use of cells smaller than mature oocytes for primary culture, the difference in imprinted gene methylation compared with parthenogenetic ESCs, and failure to establish the ESC-like cells by primary follicle culture collectively suggested the irrelevancy to gametes. CONCLUSION(S): Coculture of adult ovarian cells with somatic fibroblasts can yield colony-forming cells having ESC-like activity, which may provide an alternative for establishing autologous stem cells from adults that can be obtained without genetic manipulation.

Requirement of leukemia inhibitory factor for establishing and maintaining embryonic stem cells in mice.

OBJECTIVE: To evaluate the necessity of leukemia inhibitory factor (LIF) in establishing and self-renewing embryonic stem cells (ESCs). DESIGN: Prospective animal model study. SETTING: Gamete and Stem Cell Biotechnology Laboratory, Seoul National University, Korea. ANIMAL(S): F1 hybrid B6D2F1 mice. INTERVENTION(S): Inner cell mass (ICM) cells of blastocysts were cultured or commercially available ESCs were maintained in LIF-free or LIF-containing medium on mouse embryonic fibroblast (MEF) feeder. MAIN OUTCOME MEASURE(S): Cell morphology, LIF concentration, and mRNA expression. RESULT(S): The MEFs themselves secreted 146.5-175.3 pg/mL LIF in LIF-free medium. The ICM cells formed ESC-like colonies on MEF feeder, and E14 and R1 ESCs were successfully maintained in LIF-free medium. Expression of the genes either mediating LIF function or regulating stemness was not altered significantly, and change in the growth of ESCs was not prominent in LIF-free medium. Neither mRNA expression of differentiation-related genes nor differentiation into embryoid body was changed in the ESCs. CONCLUSION(S): Addition of LIF to culture medium is not necessary for establishing ICM-derived ESC-like colonies in the presence of fibroblast monolayer, and established ESCs can be maintained in an LIF-free medium.