Why did BPC-157 scratch closure plateau at day 14?

Contact inhibition is my first guess. Did you re-scratch teh same wells at day 7? Otherwise the closure metric saturates.

Not sure it's contact inihbition. I had a similar plateau in chondrocytes after re-scratch, and media glucose was under 1 g/L by day 8.

The PCNA rise without collagen I is the odd part. Did you stain for CD90 or tenomodulin? Fibroblast overgrowth could mask tenocyte response.

Passage 3 can do that. My p3 tenocytes had lower basal collagen I than p1, vehicle included. Did you run p1 side by side?

What was your FBS lot? We had two lots where migration stalled around day 6-7, not the peptide. New lot, effect shrank.

I ran a 12-day scratch, 8 wells/group, same 10 ng/mL, and saw an early boost. Re-scratch at day 6 kept a small gap, but vehicle also sped up, so I stopped trusting the first closure slope. My hunch is serum carryover plus edge effects. Did you use silicone inserts or pipette scratch?

With pipette scratches, the first 24h edge can look cleaner and inflate closure. Also, what was vehicle closure at 24h compared with treated? If vehicle is already 60-70% closed, the early effect may be mostly serum and not the peptide.

Normalize to total protein. PCNA can track loading, not confluence.

Every 12–14 day flattening I've chased in a scratch assay turned out to be evaporation long before it was biology, and the tell is stupidly simple: check the outer ring versus the inner wells separately. We ran a 24-well scratch setup a while back and edge wells stalled around day 12–13 while inner wells kept crawling to day 17, with phenol red drifting orange and maybe 1–2 µL less volume by the end — if your day-10 lysates came off the perimeter wells, that alone looks like a treatment effect quietly dying.

Second thing I'd poke at is the mask, not the cells: once the gap drops under roughly 300 µm the front cells start sliding over each other and a manual threshold calls it "closed" while the edge is still two or three layers thick, so reimage the exact same coordinates and ask whether the leading edge is still a single cell thick. And the boring one nobody likes — was your day-10 PCNA blot the same wells you scratched, or a sister plate?

Primary tenocytes at P3 can flip toward a more synthetic, less collectively-migratory phenotype pretty fast, and a lot of what people read as contact inhibition is really "these aren't the same cells that started the assay." What do the day-14 edges actually look like up close, rounded and piled or flat and spread? (I mostly lurk here for the GLP side of things, this is just the day job.)

I'd push back on the contact-inhibition read — the PCNA-up/collagen-flat split smells like serum-driven dedifferentiation to me. I had primary tenocytes do exactly that: 10% FBS the whole run, PCNA blazing by day 10, collagen I barely a smudge, and closure flatlined around day 12–14.

What unstuck it was dropping to 2% FBS after day 3, adding 50 µg/mL ascorbate-2-phosphate, and re-feeding every 48 h instead of every 72; collagen I finally showed up around day 12 and closure crawled to ~85% by day 18. If you're keeping high serum for the whole assay, the cells are happy to proliferate but not lay down matrix, and the scratch edge piles up enough to look contact-inhibited.

What's your feeding schedule and are you scratching a mature monolayer or day-after-seeding? n=4 with primary tenocytes can also hide a lot of well-to-well variation if your day-0 widths aren't within ~10%.

If collagen I was flat in lysate but closure stalled, I'd check the insoluble fraction. Tenocytes dump collagen into the matrix and it won't show on a standard RIPA blot. Acid extraction or hydroxyproline from the well might tell you more.

Also, did you re-scratch at day 7? Past that point you're not really measuring migration, you're measuring whatever survived P3 on plastic. They drift.

What coating are you on — plain plastic or collagen/fibronectin? That changes the migration vs proliferation read more than people admit.

Scientist-brain aside (I only get lab time between snack runs): did you check mycoplasma? I had a primary-cell scratch plateau around day 12–14, treated wells looked “active” (PCNA up) while matrix markers stalled, and it turned out contaminated.

Also worth measuring glucose/lactate at day 6/10 — pH 7.2 at harvest can hide a mid-run swing. What’s your media change schedule? With n=4 primary tenocytes, a small well-to-well nutrient dip can flatten both curves.

yo, late-night plate checker here. did you log spent-media pH or phenol red hue on the non-imaged wells? i've had scratch assays go flat around d10-14 when local glycolytic waste acidified the monolayer, especially with primary cells at p3. starting pH 7.2 means nothing if it drifts after feeding.

also check if the treated wells had more floating debris/cell clumps at the wound edge — area closure can stall while nuclei keep increasing, so DAPI count in the gap might split the difference. what's your media change schedule and did you use HEPES vs bicarbonate? that'd be my next check before blaming batch drift.

Not a tenocyte person, but I did a lot of scratch assays before maintenance brain took over. Did you save day-0 images right after the scrape? If treated wells had cleaner edges or less debris, early closure can look better without real migration.

At plateau, are cells piling up behind the front instead of filling it? A live-cell track or EdU pulse would separate motility from proliferation. Also, same FBS lot and plate coating throughout?

Serum lot/coating changes can flatten tenocyte migration more than treatment does. Just my two cents.

Hi, vey new here, so this may be off. Could it be nutrient depletion in the wells? Primary tenocytes can outpace media by ~day 10–14, and migration stalls before actual confluence.

Did you measure glucose/lactate in spent media, or change media on a set schedule? I only track things casually, but when I’ve done scratch-type wound tracking, timing of media refresh changed everything.

Also, were all wells from the same FBS lot and same passage split? Even small serum lot shifts can flatten the later curve.

Did you randomize plate positions to rule out incubator gradients?

Phase-contrast "open" area can lie. At that density tenocytes lay down provisional matrix, and you get cell-free draped layers that still read as a gap.

Fix and stain — crystal violet or DAPI — before trusting the day-14 plateau; I've had wells look 40% open on phase and be fully covered on stain. Also, were you imaging fixed coordinates daily or re-finding the scratch each time? ROI drift alone can fake a plateau.

Not tenocyte-specific, but I track assay runs like I track stock: same lot, same day, same tip. Did you use the same FBS lot and collagen-coating batch for both arms?

A lot switch can bump PCNA without moving collagen I, then both flatten once cells hit edge confluence. Also, what was your initial gap width in µm, and did you normalize to each well’s own day 0?

Uneven starting gaps can make a “plateau” that’s just slow wells pulling the mean. Log media volume per well too—edge evaporation can mimic contact inhibition by day 10–14.

Tbh two kids here, so my brain is mostly snack-drawer logistics, but I’d check plate position/evaporation first. Fourteen days in a plate, outer wells can dry down and look stalled while inner wells keep going.

Were treated and vehicle wells spread evenly across inner/outer wells, or was one group all in one row/column? If so, that’s a confound. Also straight lysate collagen I can miss deposited matrix—did you compare soluble vs insoluble?

love the n=4 and day-by-day tracking. One thing I’d check: was the peptide a one-time spike at day 0, or refreshed with media changes?

At 37°C in serum-containing medium, peptides can adsorb/degrade, so days 0–6 might jst be the window where active peptide is present; after that both groups look like vehicle. If you refresh, does the treated curve separate again?

Also, a short proliferation-arrest or low-serum arm would tell you whether the late plateau is proliferation or just migration running out of steam. What’s your media-change schedule?

Not tenocyte-specific, but I’d separate migration from proliferation before blaming contact inhibition. If PCNA is up while collagen I is flat, you may just have more cells piling up, not functional repair.

A low-serum or proliferation-arrested scratch arm would tell you whether the day 6–14 flattening is migration stalling. Also, P3 primary tenocytes can drift; did you check tenomodulin/scleraxis vs P0?

If they’re down, the plateau may be phenotype loss, not assay saturation. I track recovery like I track lifts—markers matter, but the outcome matters more.