study #1 - not blinded. essentially a case series. 28% failure rate. researchers stated this was level 4 evidence.
study #2 - a much better study. randomized, but why use hyaluronidase and bone marrow? the volumes were different in all 3 groups (4ml for HA alone, 5.5 for the low dose BM-MSC, and 7ml for high dose). they also used pelvic bone marrow to culture the cells. and I do not see anywhere that "control patients" had BM biopsy done - doesn't specifically state. if not, then possible observer bias/patient bias? also, why do the WOMAC pain scores not correlate with VAS pain scores (in the WOMAC data, it notes that HA group had pain reduction similar to BM-MSC groups, but not VAS). overall, not a bad study, small in size. best of the bunch, but still limited in size and has some questionable decisions by the researchers.
study #3 - case report. laden with observer bias.
study #4 - you forgot to include the statement before that which you chose to post, in particular: " All patients were partly satisfied with the results of the study. Pain, functional status of the knee, and walking distance tended to be improved up to six months post-injection, after which pain appeared to be slightly increased and patients' walking abilities slightly decreased."
study #5 - a pilot study only.
study #6 - small group as before, but this time, lets do a bunch of different sites all over the body!! that will be different, and prove that BM-MSC works!
interestingly, this same Iranian group applied for a clinical study for OA of hip, in 2011, that was apparently completed but never reported (maybe because it failed?)...
Mesenchymal Stem Cell Transplantation in Osteoarthritis of Hip Joint - No Study Results Posted - ClinicalTrials.gov
study #7 - adding another therapy - not only HA, or BM/MSC, but ALSO LETS DO SOME DRILLING!!! 5 patients, like all the other studies besides #2, not blinded, not controlled. not randomized.
study #8 - only high dose group had benefit at 6 months out...
long and short - double blinded randomized trial comparing BM-MSC with HA and with sham injection is what is most evidentiary...