Cell Biology Questions

hroderick · April 2018

My understanding may be wrong and I'd like to know what is right
> Nerve and brain cells are finite, once broken never repair or replicate
> Skin cells are constantly being replaced with new ones.

And questions are about fat and muscle cells
> Are fat cells like nerve cells, they fill and deflate but never go away? Do they replicate and increase in number?
> Do muscle cells break then repair to become stronger? Do they replicate? Do they disappear or shrink?

I may have picked up some odd wrong ideas and repeated above. I'm sure there are very complex and rare exceptions. I would appreciate simple confirmation or explanation from someone who really knows. Then the followup question, how should this influence my body management decisions?

Thanks in advance for explanations and advice

Cherimoose · April 2018

Fat cells don't go away. They can replicate during weight gain, especially in kids.. which is one reason to avoid childhood obesity.

Skin cells can multiply during weight gain too. New skin cells don't go away without surgery.

Muscle cells can multiply, but that's uncommon in adults. The cells can grow bigger or shrink, depending on use or lack of it.
Bones, by the way, can increase & decrease cell numbers. Bones can get either denser or thicker, depending on the loading. Compressive forces favor density, sideways forces favor thickness.

The brain can make new neural connections to compensate for damage elsewhere. The media shows examples of this regularly, with people with brain injuries.
Nerves elsewhere in the body may or may not repair, depending on the damage.

Why do you ask?

hroderick · April 2018

Thanks.

I was wondering about fat cells and that got me wondering about muscle cells too. I guess fat cells can get pretty big or pretty small. I have a couple of lipomas which I though were single fat cells run amock, but apparently are not.

Being over 60 and on my way to losing 150lb, almost half my max weight, I'm concerned what shape my skin would be in. I'm not vain, masochistic, or rich enough to remove it, so I'll just tie it up like a pony tail in the back. I'd rather be having retirement outdoor adventures with a tail than driving an electric wheelchair around walmart.

I guess if the fat cells remain, I'll become be a fat man that is thin. My ancestors must have survived many famines.

JeromeBarry1 · May 2018

Fat children add fat cells as they keep demonstrating to their "brain in a growing body" that they need more. As adults, they stop adding new fat cells. However, as adults, they can lose weight like anyone but they can add it back very fast.

lynn_glenmont · May 2018

Apparently muscle cells do increase, from the replication and differentiation of satellite cells.

https://www.unm.edu/~lkravitz/Article folder/musclesgrowLK.html

And skin cells are constantly dying. That's what most of the dust in your house is. Dead skin.

deannalfisher · May 2018

@Aaron_K123 maybe can answer - he provides lots of good science because he is all edumacated in it

Aaron_K123 · May 2018

deannalfisher wrote: »

@Aaron_K123 maybe can answer - he provides lots of good science because he is all edumacated in it

Molecular biologist, not cell biologist but I mean I've taken courses in cell bio so I can take a crack at answering although I may get some things wrong as I am writing this on my phone from memory and not cross checking it with texts.

Cells that can replicate without end are referred to as being "immortal". The only cells in your body that are immortal are stem cells in your bone marrow or, heaven forbid, cancer cells which have become immortalized through mutation of regulatory pathways.

All the different cell types in your body are derived from stem cells...stem cells change into them in a process called differentiation. Some cell types can replicate themselves but a limited number of times while others cannot. The number of times a cell can replicate is related to sections of DNA at the ends of chromosomes called telomeres.

Skin cells, fat cells and muscle cells are capable of limited self replication while nerve cells are not capable of replication at all. In theory though any cell can be replaced by a stem cell differentiating into that cell type.

Now fat cells are called adipose cells. They contain a large vacuole in the cell that contains fat. That cell can be full of fat or can be empty awaiting fat deposits or any state in between. If all of your adipose cells fill with fat then presumably some would replicate to make more storage. If you then lose a ton of weight your adipose cells will become empty....but they are still there, they are just empty. Think of them like storage tanks. Sure, you can make more storage tanks...but you don't have to unless all your existing storage is full.

Once a cell is differentiated though it has a clock basically and will only live for so long and can only divide for so many times before it can no longer replicate. The exception being cancer cells....which is why research tends to use cancer cell lines, because you can keep making more and more from the original stock without end. Normal cells you can only make so many before they stop being able to replicate.

deannalfisher · May 2018

i couldn't remember your background - all i know is that i can barely spell biology

grinning_chick · May 2018

hroderick wrote: »

Thanks.

I was wondering about fat cells and that got me wondering about muscle cells too. I guess fat cells can get pretty big or pretty small. I have a couple of lipomas which I though were single fat cells run amock, but apparently are not.

The adipocytes (fat cells) that form the abnormal "lumps and bumps" of lipomas are not normal adipose (fat) tissue cells. There are multiple subtypes of lipomas out there.

Generally speaking, lipomas are a group of adipocytes "gone wild", so to speak. While they are still tumors, they are benign ones versus a malignant tumor (cancer). And while not a cancer, the adipocytes that comprise lipomas are not 100% normal, biologically speaking. Namely, you can see mitosis (cell division) of the adipocytes forming a lipoma in some of them. It is not usually a very high rate of mitosis (mitotic index), but it does happen. You can also see angiogenesis (new blood vessels created to feed the tumor) in some of them. As such, some lipomas grow by both an increase in the individual cell's size as well as cell number.

So, yeah, technically you are increasing the number of white fat cells you have as an adult when you grow some lipomas. Not all lipomas, though, as there are some lipomas where evidence of mitosis is not observed to occur.

Doctors frequently act like abnormal growths of adipocytes are harmless...because the majority of the time they are lipomas and so that is true (unless they get very large and start impinging/compressing/strangulating things externally or internally). But there *are* malignant tumors (cancer) of adipocytes; they are called liposarcomas - a soft tissue sarcoma arising from adipose tissue.

Also, while lipomas do not turn *into* liposarcomas, you can have a lipoma grow next to/around/superficial to/envelope a liposarcoma. Seen that before. That is why some suspected lipomas, if the history/location/biology warrant it, should be tested by biopsy histopathology vs. fine needle aspirate (FNA) as a FNA is a teeny weeny sample and can easily miss a liposarcoma. Heck, even with histopath, a liposarcoma can still be missed if the mass removed is large and the section of the tumor taken and submitted misses it.

Finally, middle aged and older human men are prone to a specific subtype of lipoma known as a pleomorphic (giant-cell) lipoma. That may be where your confusion arose, OP. You heard "giant-cell" and, literally, thought it was a tumor comprised of one giant cell. They are not. They are still multi-cellular, comprised of many cells. But what they are not, are liposarcomas, although they can simulate closely enough that it triggers biopsy/histopath to make sure it is "just" a lipoma after all.

Aaron_K123 · May 2018

@deannalfisher I think we just found you someone to point cell biology questions to @grinning_chick. Sounds like perhaps a medical/histology background?

deannalfisher · May 2018

Apparently! I’m sure I can find other science-y questions for you

PAV8888 · May 2018

grinning_chick wrote: »

Finally, middle aged and older human men are prone to a specific subtype of lipoma known as a pleomorphic (giant-cell) lipoma. That may be where your confusion arose, OP. You heard "giant-cell" and, literally, thought it was a tumor comprised of one giant cell. They are not. They are still multi-cellular, comprised of many cells. But what they are not, are liposarcomas, although they can simulate closely enough that it triggers biopsy/histopath to make sure it is "just" a lipoma after all.

So, err, Ms @grinning_chick when will all my empty milk jugs fat cells call it a day and stop screaming that they would like to be filled again and go into @Aaron_K123's and CNN's "exhalation heaven"** And if not... why not? And should I want them to? Or should I actually be happy that they're sitting there on empty as opposed to waving bye-bye?

**subtle reference to a post Aaron made about where your fat goes when you loose it! The same information was also featured on CNN within a week, or so, of Aaron's post!

hroderick · May 2018

Thanks again to the MFP community for quality answers

JeromeBarry1 · May 2018

PAV8888 wrote: »

grinning_chick wrote: »

Finally, middle aged and older human men are prone to a specific subtype of lipoma known as a pleomorphic (giant-cell) lipoma. That may be where your confusion arose, OP. You heard "giant-cell" and, literally, thought it was a tumor comprised of one giant cell. They are not. They are still multi-cellular, comprised of many cells. But what they are not, are liposarcomas, although they can simulate closely enough that it triggers biopsy/histopath to make sure it is "just" a lipoma after all.

So, err, Ms @grinning_chick when will all my empty milk jugs fat cells call it a day and stop screaming that they would like to be filled again and go into @Aaron_K123's and CNN's "exhalation heaven"** And if not... why not? And should I want them to? Or should I actually be happy that they're sitting there on empty as opposed to waving bye-bye?

**subtle reference to a post Aaron made about where your fat goes when you loose it! The same information was also featured on CNN within a week, or so, of Aaron's post!

So you're the guy watching CNN!

serindipte · May 2018

This thread got me curious and I found this. Interesting read (I thought, anyway), though it sucks to know that fat cells do die off only to be replaced with new ones... You'd think, if we lost the weight and there were empty fat cells hanging out, the dead ones wouldn't need to go zombie on us, right?

http://book.bionumbers.org/how-quickly-do-different-cells-in-the-body-replace-themselves/

PAV8888 · May 2018

JeromeBarry1 wrote: »

PAV8888 wrote: »

grinning_chick wrote: »

Finally, middle aged and older human men are prone to a specific subtype of lipoma known as a pleomorphic (giant-cell) lipoma. That may be where your confusion arose, OP. You heard "giant-cell" and, literally, thought it was a tumor comprised of one giant cell. They are not. They are still multi-cellular, comprised of many cells. But what they are not, are liposarcomas, although they can simulate closely enough that it triggers biopsy/histopath to make sure it is "just" a lipoma after all.

So, err, Ms @grinning_chick when will all my empty milk jugs fat cells call it a day and stop screaming that they would like to be filled again and go into @Aaron_K123's and CNN's "exhalation heaven"** And if not... why not? And should I want them to? Or should I actually be happy that they're sitting there on empty as opposed to waving bye-bye?

**subtle reference to a post Aaron made about where your fat goes when you loose it! The same information was also featured on CNN within a week, or so, of Aaron's post!

So you're the guy watching CNN!

Wasn't it YOU who posted the article from CNN.com that echoed what Aaron was saying while stating that most health professionals don't know what happens when fat gets lost?

hroderick · August 2018

This scientific article tells a different story. Fat cells do die and go away. The trick is to stop creating replacements with a calorie balance or deficit. I don't know how long it takes for a fat cell to begin, die, and disappear...but I'm glad they do

https://cell.com/cell/pdf/S0092-8674(12)00775-1.pdf

CSARdiver · August 2018

I'm not sure if any of this matters to a degree where this would be observable.

I believe the concern to be that one with more fat cells holds a higher chance of "yo-yoing" and regaining undesired body fat, but clinical studies shows very weak correlation and no clear causation.

The percentage of differentiation is so minute when you consider the overall number of cells.

You would find a similar distribution of muscle cells and the phenomenon of "hard gainers". A small degree of this is genetic, but the majority is environment and conditioning.

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